Display device, manufacturing method thereof, and television receiver

ABSTRACT

The present invention discloses a method for manufacturing a display device comprising the steps of forming a first film pattern using a photosensitive material over a substrate, forming a second film pattern in such a way that the first film pattern is exposed by being irradiated with a laser beam, modifying a surface of the second film pattern into a droplet-shedding surface, forming a source electrode and a drain electrode by discharging a conductive material to an outer edge of the droplet-shedding surface by a droplet-discharging method, and forming a semiconductor region, a gate-insulating film, and a gate electrode over the source electrode and the drain electrode.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a display device including a thin filmtransistor formed by a droplet-discharging method typified by anink-jetting method and relates to a method for manufacturing the displaydevice.

2. Related Art

A display panel including a thin film transistor (hereinafter alsoreferred to as a TFT) over a substrate, which is so-called an activematrix display panel, has been conventionally manufactured by patterningvarious thin films according to a photolithography process using aphotomask in the same way as a manufacturing technique of asemiconductor integrated circuit.

In other words, the TFT can be manufactured by forming the thin filmpattern as follows. After applying resist all over the substrate,prebake is performed to the resist, and then an ultraviolet ray or thelike is irradiated thereto in order to expose the resist and to form aresist pattern according to the photolithography process. After that, afilm (a film formed of a semiconductor material, an insulating material,or a conductive material) existing in the part not to be the thin filmpattern is etched a way using the resist pattern as a mask. Thus, thethin film pattern is formed.

When a glass substrate or a display panel is small, the patterning canbe performed comparatively easily by an exposure apparatus. However,with the increase of the size of the substrate, it becomes impossible toexpose the whole surface of the display panel in one exposure process.As a result, a method has been developed in which the whole surface ofthe substrate is exposed in such a way that the region with thephotoresist applied is divided into several blocks and then the exposureis made to the respective blocks sequentially (for example, refer toJapanese Patent Document Laid-Open No. H11-326951).

In manufacturing a semiconductor device, it has been examined to employa droplet-discharging apparatus to pattern a thin film and a wiring usedin the TFT for the purpose of reducing the cost of the facility andsimplifying the process.

Japanese Patent Document Laid-Open No. 2000-188251 discloses a techniquefor forming a film over a semiconductor wafer with the use of anapparatus that can discharge resist having a narrow line shapecontinuously from a nozzle in order to suppress the consumption of theliquid required to form the film.

The droplet may have a small diameter in order to form the TFT havingthe small size by the drop-discharging method according to JapanesePatent Document Laid-Open No. 2000-188251. For this purpose, the nozzlemay have the small diameter. In this case, however, a composition of thedischarging droplet is clogged in the top of the nozzle due to adhesion,drying, or solidification of the composition, and therefore it isdifficult to discharge a constant amount of droplet stably andcontinuously. This causes problems of low throughput and low yield ofthe semiconductor device formed by using the TFT.

SUMMARY OF THE INVENTION

The present invention is made in view of these problems, and the objectof the present invention is to provide a method for manufacturing a TFThaving a fine structure by using the nozzle not having a small diameter.Moreover, another object of the present invention is to provide a methodfor manufacturing a semiconductor device with high throughput and highyield at low cost. The present invention discloses a method formanufacturing a display device comprising the steps of forming a thinfilm, discharging or applying a photosensitive resin (resist) over thethin film, forming a resist mask by irradiating the photosensitive resinwith a laser beam, forming a thin film pattern having a desired shape byetching the thin film using the resist mask, and making a part of adroplet-shedding surface into a droplet-attracting surface using thethin film pattern.

The present invention discloses another method for manufacturing adisplay device comprising the steps of discharging or applying aphotosensitive resin, forming a pattern by a step of irradiating thephotosensitive resin with a laser beam, and performing adroplet-shedding process to the pattern of the photosensitive resin.

The present invention discloses another method for manufacturing adisplay device comprising the step of forming a droplet-shedding regionand a droplet-attracting region in such a way that a part of thedroplet-shedding region is irradiated with a laser beam so that the partirradiated with the laser beam becomes the droplet-attracting region.

Moreover, the present invention includes the following structure.

The present invention discloses another method for manufacturing adisplay device comprising the steps of forming a first film pattern overa substrate by using a photosensitive material, forming a second filmpattern in such a way that the first film pattern is developed afterbeing irradiated with a laser beam, modifying a surface of the secondfilm pattern into a droplet-shedding surface, forming a source electrodeand a drain electrode by discharging a conductive material to an outeredge of the droplet-shedding surface according to a droplet-dischargingmethod, and forming a semiconductor layer, a gate insulating film, and agate electrode over the source electrode and the drain electrode.

The present invention discloses another method for manufacturing adisplay device comprising the steps of forming a first film pattern overa substrate by using a solution for forming a droplet-shedding surface,forming a second film pattern having a droplet-shedding region and adroplet-attracting region by irradiating the first film pattern with alaser beam so as to change the droplet-shedding region into thedroplet-attracting region, forming a source electrode and a drainelectrode by discharging a conductive material over a surface of thedroplet-shedding region according to a droplet-discharging method, andforming a semiconductor layer, a gate insulating film, and a gateelectrode over the source electrode and the drain electrode.

The present invention discloses another method for manufacturing adisplay device comprising the steps of forming a first film pattern overa light-transmitting substrate by a droplet-discharging method,discharging or applying a photosensitive material over the first filmpattern, forming a mask pattern in such a way that a region where thefirst film pattern and the photosensitive material are superposed isdeveloped after being irradiated with a first laser beam, forming a gateelectrode having a desired shape by etching the first film pattern usingthe mask pattern, forming a first insulating film over the gateelectrode, forming a droplet-shedding surface over the first insulatingfilm, modifying a part of the droplet-shedding surface into adroplet-attracting surface by irradiating the part of thedroplet-shedding surface with a second laser beam transmitted throughthe light-transmitting substrate, forming a source electrode and a drainelectrode over the droplet-attracting surface, the gate electrode, andthe first insulating film, and forming a semiconductor layer over thedroplet-shedding surface.

The present invention discloses another method for manufacturing adisplay device comprising the steps of forming a first film pattern overa light-transmitting substrate by a droplet-discharging method,discharging or applying a photosensitive material over the first filmpattern, forming a mask pattern in such a way that a region where thefirst film pattern and the photosensitive material are superposed isdeveloped after being irradiated with a first laser beam, forming a gateelectrode having a desired shape by etching the first film pattern usingthe mask pattern, forming a first insulating film over the gateelectrode, forming a semiconductor layer over the first insulating film,forming a droplet-shedding surface over a surface of the firstinsulating film and the semiconductor layer, modifying a part of thedroplet-shedding surface into a droplet-attracting surface byirradiating the part of the droplet-shedding surface with a second laserbeam transmitted through the light-transmitting substrate, forming asource electrode and a drain electrode over the droplet-attractingsurface, and forming a source region and a drain region by etching apart of the semiconductor layer while using the source electrode and thedrain electrode as a mask.

The present invention discloses another method for manufacturing adisplay device comprising the steps of forming a first film pattern overa light-transmitting substrate by a droplet-discharging method,discharging or applying a photosensitive material over the first filmpattern, forming a mask pattern in such a way that a region where thefirst film pattern and the photosensitive material are superposed isdeveloped after being irradiated with a first laser beam, forming a gateelectrode having a desired shape by etching the first film pattern usingthe mask pattern, forming a first insulating film over the gateelectrode, forming a first semiconductor layer over the first insulatingfilm, forming a second insulating film over the first semiconductorlayer, forming a second semiconductor layer over the first semiconductorlayer and the second insulating film, forming a droplet-shedding surfaceover surfaces of the first insulating film and the second semiconductorlayer, modifying a part of the droplet-shedding surface into adroplet-attracting surface by irradiating the part of thedroplet-shedding surface with a second laser beam transmitted throughthe light-transmitting substrate, forming a source electrode and a drainelectrode over the droplet-attracting surface, and forming a sourceregion and a drain region by etching the second semiconductor layerwhile using the source electrode and the drain electrode as a mask.

In the present invention, the first laser beam has a wavelength in therange of an ultraviolet region to an infrared region, and the secondlaser beam has a wavelength in the range of an ultraviolet to infraredregion.

The photosensitive material is a negative photosensitive resin or apositive photosensitive resin.

Moreover, the present invention discloses a television having a displaydevice formed by the above method for manufacturing the display device.

It is noted that the display device is a liquid crystal display deviceor a light-emitting device.

ADVANTAGEOUS EFFECT OF THE INVENTION

The present invention can miniaturize the thin film pattern in the caseof using the droplet-discharging method when the droplet-sheddingprocess is performed in combination with a droplet-shedding process andpartly changing the droplet-shedding surface into a droplet-attractingsurface by the laser irradiation. For example, even a minute control ofa space between the source wiring and the drain wiring over thechannel-forming region of the TFT becomes possible, and thecharacteristic of the TFT can be enhanced.

Moreover, a TFT having the fine structure can be formed even when thediameter of the nozzle is not small in particular. A highly integratedcircuit and a semiconductor display device such as a display devicehaving high aperture can be manufactured using the TFT with highthroughput and high yield at low cost.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a top view for explaining a structure of a display panel ofthe present invention;

FIG. 2 is a top view for explaining a structure of a display panel ofthe present invention;

FIG. 3 is a top view for explaining a structure of a display panel ofthe present invention;

FIGS. 4A to 4C are cross-sectional views for explaining a manufacturingprocess of an EL display panel of the present invention;

FIGS. 5A to 5C are cross-sectional views for explaining a manufacturingprocess of an EL display panel of the present invention;

FIGS. 6A to 6C are cross-sectional views for explaining a manufacturingprocess of an EL display panel of the present invention;

FIGS. 7A to 7C are cross-sectional views for explaining a manufacturingprocess of an EL display panel of the present invention;

FIGS. 8A to 8C are cross-sectional views for explaining a manufacturingprocess of an EL display panel of the present invention;

FIG. 9 is a cross-sectional view for explaining a manufacturing processof an EL display panel of the present invention;

FIGS. 10A to 10C are cross-sectional views for explaining amanufacturing process of an EL display panel of the present invention;

FIG. 11 is a cross-sectional view for explaining a manufacturing methodof a liquid crystal display panel of the present invention;

FIG. 12 is a top view for explaining a manufacturing process of an ELdisplay panel of the present invention;

FIG. 13 is a top view for explaining a manufacturing process of an ELdisplay panel of the present invention;

FIG. 14 is a top view for explaining a manufacturing process of an ELdisplay panel of the present invention;

FIG. 15 is a top view for explaining a manufacturing process of an ELdisplay panel of the present invention;

FIG. 16 is a cross-sectional view for explaining a manufacturing processof an EL display panel of the present invention;

FIG. 17 is a top view for explaining an EL display panel of the presentinvention;

FIG. 18 is an equivalent circuit diagram of the EL display panelexplained in FIG. 17;

FIGS. 19A and 19B are drawings for explaining a light-emitting elementapplicable in the present invention;

FIGS. 20A and 20B are drawings for explaining a light-emitting elementapplicable in the present invention;

FIGS. 21A and 21B are drawings for explaining a method for mounting adriver circuit of a display panel of the present invention;

FIGS. 22A and 22B are drawings for explaining a method for mounting adriver circuit of a display panel of the present invention;

FIGS. 23A to 23F are circuit diagrams for explaining a pixel structureapplicable in an EL display panel of the present invention;

FIG. 24 is a drawing for explaining a circuit structure in the case offorming a scanning line driver circuit with the use of a TFT in adisplay panel of the present invention;

FIG. 25 is a drawing for explaining a circuit structure in the case offorming a scanning line driver circuit with the use of a TFT in an ELdisplay panel of the present invention (a pulse output circuit);

FIG. 26 is a drawing for explaining a circuit structure in the case offorming a scanning line driver circuit with the use of a TFT in adisplay panel of the present invention (a buffer circuit);

FIG. 27 is a drawing for explaining a structure of a droplet-dischargingsystem applicable in the present invention;

FIG. 28 is a cross-sectional view for explaining an EL display panel ofthe present invention;

FIG. 29 is a cross-sectional view for explaining an example of astructure of an EL display module of the present invention;

FIG. 30 is a cross-sectional view for explaining an example of astructure of an EL display module of the present invention;

FIG. 31 is a block diagram for showing a main structure of a televisionreceiver of the present invention;

FIG. 32 is a drawing for explaining a television receiver completed bythe present invention;

FIG. 33 is a drawing for explaining a structure of a laser direct imagesystem applicable in the present invention;

FIGS. 34A and 34B are cross-sectional views for explaining amanufacturing process of an EL display panel of the present invention;

FIGS. 35A and 35B are cross-sectional views for explaining amanufacturing process of an EL display panel of the present invention;

FIGS. 36A and 36B are cross-sectional views for explaining amanufacturing process of an EL display panel of the present invention;

FIGS. 37A and 37B are cross-sectional views for explaining amanufacturing process of a display panel of the present invention;

FIG. 38 is a cross-sectional view for explaining a manufacturing processof a display panel of the present invention;

FIGS. 39A and 39B are cross-sectional views for explaining amanufacturing process of a display panel of the present invention;

FIGS. 40A and 40B are cross-sectional views for explaining amanufacturing process of a display panel of the present invention;

FIGS. 41A and 41B are cross-sectional views for explaining amanufacturing process of a display panel of the present invention;

FIGS. 42A and 42B are cross-sectional views for explaining amanufacturing process of a display panel of the present invention;

FIGS. 43A and 43B are cross-sectional views for explaining amanufacturing process of a display panel of the present invention;

FIGS. 44A and 44B are cross-sectional views for explaining amanufacturing process of a display panel of the present invention;

FIGS. 45A and 45B are cross-sectional views for explaining amanufacturing process of a display panel of the present invention;

FIGS. 46A and 46B are cross-sectional views for explaining amanufacturing process of a display panel of the present invention;

FIGS. 47A to 47C are cross-sectional views for explaining amanufacturing process of a liquid crystal display panel of the presentinvention;

FIGS. 48A to 48C are cross-sectional views for explaining amanufacturing process of a liquid crystal display panel of the presentinvention;

FIGS. 49A to 49C are cross-sectional views for explaining amanufacturing process of a liquid crystal display panel of the presentinvention;

FIGS. 50A to 50C are cross-sectional views for explaining amanufacturing process of a liquid crystal display panel of the presentinvention;

FIGS. 51A to 51C are cross-sectional views for explaining amanufacturing process of a liquid crystal display panel of the presentinvention;

FIGS. 52A and 52B are cross-sectional views for explaining amanufacturing process of a liquid crystal display panel of the presentinvention;

FIGS. 53A to 53C are cross-sectional views for explaining amanufacturing process of a liquid crystal display panel of the presentinvention;

FIGS. 54A to 54C are cross-sectional views for explaining amanufacturing process of a liquid crystal display panel of the presentinvention;

FIG. 55 is a cross-sectional view for explaining a manufacturing processof a liquid crystal display panel of the present invention;

FIG. 56 is a top view for explaining a manufacturing process of a liquidcrystal display panel of the present invention;

FIG. 57 is a top view for explaining a manufacturing process of a liquidcrystal display panel of the present invention;

FIG. 58 is a top view for explaining a manufacturing process of a liquidcrystal display panel of the present invention;

FIG. 59 is a top view for explaining a manufacturing process of a liquidcrystal display panel of the present invention;

FIGS. 60A and 60B are drawings for explaining a method for mounting adriver circuit of a display panel (COG method) of the present invention;

FIG. 61 is a drawing for explaining a structure of a display module ofthe present invention;

FIG. 62 is a top view for explaining a liquid crystal display panel ofthe present invention;

FIG. 63 is an equivalent circuit diagram of a display panel explained inFIG. 26;

FIG. 64 is a cross-sectional view for explaining a display panel of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

Embodiment modes of the present invention are hereinafter explained withreference to drawings. Since the present invention can be embodied inmany different modes, it is easily understood by those skilled in theart that the modes and the details of the present invention can bechanged and modified in various ways unless such changes andmodifications depart from the scope and the content of the presentinvention hereinafter defined. Therefore, the present invention is notlimited to the description of the embodiment modes. The same referencenumerals are given to the same part throughout the drawings, and theexplanation to the same parts is omitted.

FIG. 1 is a top view for showing a structure of a display panel of thepresent invention. A pixel portion 101 in which pixels 102 are arrangedin a matrix form, an input terminal 103 on a scanning line side, and aninput terminal 104 on a signal line side are formed over a substrate 100having an insulating surface. The number of pixels may be determinedbased on various needs. It may be 1024×768×3 (RGB) in the case of XGA,and it may be 1600×1200×3 (RGB) in the case of UXGA. It may be1920×1080×3 (RGB) in the case of a full-spec high definition.

When the display panel of the present invention is an EL display panel,the pixels 102 are arranged in a matrix format intersection points ofscanning lines and signal lines. The scanning lines extend from theinput terminal 103 on the scanning line side, and the signal linesextend from the input terminal 104 on the signal line side. Each of thepixels 102 is provided with a transistor for controlling a connectionstate with the signal line (hereinafter this transistor is also referredto as a switching transistor or a switching TFT in case of using a TFTas the transistor) and a transistor for controlling current supplying toa light-emitting element (hereinafter this transistor is also referredto as a driver transistor or a driver TFT in case of using a TFT as thetransistor), and the driver transistor is serially connected to thelight-emitting element.

When the display panel of the present invention is a liquid crystaldisplay panel, the pixels 102 are also arranged in a matrix form atintersection points of scanning lines and signal lines. The scanninglines extend from the input terminal 103 on a scanning line side, andthe signal lines extend from the input terminal 104 on the signal lineside. Each of the pixels 102 is provided with a switching element and apixel electrode connected to the switching element. A typical example ofthe switching element is a TFT. When a gate electrode of the TFT isconnected with the scanning line and when one of a source and a drain ofthe TFT is connected with the signal line, the respective pixels can becontrolled independently by a signal input from the outside.

The main components of the TFT are a semiconductor layer, agate-insulating layer, and a gate electrode layer, followed by anadditional component such as a wiring to be connected to the sourceregion or the drain region formed in the semiconductor layer. As thestructure of the TFT, two structures are typically known. One of them isa top-gate structure in which the semiconductor layer, thegate-insulating layer, and the gate electrode layer are formed in orderfrom the substrate side, and the other is a bottom-gate structure inwhich the gate electrode layer, the gate-insulating layer, and thesemiconductor layer are formed in order from the substrate side. In thepresent invention, any structure may be employed.

The material for forming the semiconductor layer may be an amorphoussemiconductor (hereinafter also referred to as an AS) manufactured by avapor growth method or a sputtering method using a semiconductormaterial gas typified by silane or germane, a poly-crystallinesemiconductor obtained by crystallizing the amorphous semiconductorwhile using photo energy or thermal energy, a semi-amorphoussemiconductor (also referred to as microcrystal and hereinafter alsoreferred to as an SAS for short), or the like.

The SAS has an intermediate characteristic between the amorphoussemiconductor and the crystalline semiconductor (the crystallinesemiconductor includes a single-crystal semiconductor and apoly-crystalline semiconductor) and has a third state that is stable infree energy. Moreover, the SAS includes a crystalline region havingshort-range order and having lattice distortion. A crystalline regionhaving a width from 0.5 to 20 nm can be observed at least in a part ofthe region in an SAS film, and the raman spectrum of Si—Si confectionshifts to the side of lower wavenumber than 520 cm⁻¹ in the case ofusing silicon as a main component. According to an X-ray diffraction, adiffraction peak of (111) and (220), which is considered to be caused bya silicon crystal lattice, is observed. As a terminating agent of adangling bond, hydrogen or halogen is included by 1 atomic % or more.The SAS can be formed by glow-discharging the silicide gas (this methodis refereed a plasma CVD method). As the silicide gas, SiH₄, Si₂H₆,SiH₂Cl₂, SiHCl₃, SiCl₄, SiF₄, or the like can be used. Moreover, GeF₄may be mixed into the above gas. Furthermore, the silicide elementsselected from the group consisting of H₂, He, Ar, Kr, and Ne by adilution ratio of 2 to 1000 times under the condition where the pressureis from approximately 0.1 to 133 Pa, the power supply frequency is from1 to 120 MHz, preferably from 13 to 60 MHz, and the substratetemperature is 300° C. or less. It is preferable that the concentrationof the impurity in the atmospheric constituent such as oxygen, nitrogen,or carbon is 1×10²⁰ atoms/cm³ or less. Particularly, the concentrationof the oxygen is set to 5×10¹⁹ atoms/cm³ or less, preferably 1×10¹⁹atoms/cm³ or less.

FIG. 1 shows a structure of the display panel in which the signals inputinto the scanning line and the signal line are controlled by an externaldriver circuit. However, driver ICs 105 and 106 may be mounted over thesubstrate 100 as a COG (Chip On Glass) as shown in FIG. 2. Moreover, thedriver ICs 105 and 106 may be formed using a single-crystalsemiconductor substrate or may be formed by a TFT over a glasssubstrate.

In addition, in the case of forming the TFT provided in the pixel withthe use of the SAS, a scanning line driver circuit 107 can be formedintegrally over the substrate 100 as shown in FIG. 3.

An example of a droplet-discharging apparatus used for patterning isshown in FIG. 27. Heads 1405 and 1412 of droplet-discharging means 1403are connected to controlling means 1407. The pattern programmed inadvance can be written by controlling the controlling means 1407 withthe use of a computer 1410. The position for writing may be determinedbased on a marker 1411, a reference point, formed over a substrate 1400.Alternatively, the reference point may be an edge of the substrate 1400.The reference point is detected by imaging means 1404 such as an imagesensor using a charge-coupled device (CCD) or a complementary metaloxide semiconductor (CMOS) and is converted into a digital signal byimage processing means 1409. Then, the digital signal is recognized bythe computer 1410 to generate a control signal, which is sent to thecontrol means 1407. The data of the pattern to be formed over thesubstrate 1400 is stored in a recording medium 1408, and the controlsignal is sent to the control means 1407 based on this data. Thus, theheads 1405 and 1412 of the droplet-discharging means 1403 can becontrolled individually. The discharged material is supplied frommaterial suppliers 1413 and 1414 to the heads 1405 and 1412 throughpipes. At present, an apparatus is examined in which a metal, an organicmaterial, and an inorganic material can be discharged separately in thesame way as RGB colors are separately discharged by one ink-jet head asEL layers. Consequently, in the case of discharging an interlayerinsulating layer or the like, the same material may be discharged formultiple times to form narrow lines in order to increase the throughput.In FIG. 27, the total length of the respective heads 1405 and 1412 ofthe droplet-discharging means 1403 is the same as the width of thesubstrate. However, even when the substrate has the width that isgreater than the total length of the respective heads 1405 and 1412 ofthe droplet-discharging means 1403, the pattern can be formed byrepeating the scanning. In this case, the same pattern can be writtenover a plurality of parts of the substrate because the heads 1405 and1412 can be scanned freely in directions indicated by arrows over thesubstrate so that the region over which the pattern is written can beset freely.

Next, a manufacturing process of a light-emitting device of the presentinvention is hereinafter explained.

Embodiment Mode 1

A method for manufacturing a bottom-gate channel-protection type TFT isexplained as the embodiment mode 1.

FIG. 4A shows a process for forming a gate electrode layer and acapacitor-wiring layer and a gate wiring layer connected to the gateelectrode layer by a droplet-discharging method. It is noted that FIG.4A shows schematically a vertical cross-sectional structure, and FIG. 12shows its plain structure corresponding to A-B, C-D and E-F of FIG. 4A.Therefore, both figures may be referred to in this embodiment mode.

A non-alkaline glass substrate such as barium borosilicate glass,alumino borosilicate glass, or aluminosilicate glass manufactured by afusion method or a floating method; a ceramic substrate; a plasticsubstrate having the heat resistance that can withstand the temperaturein this manufacturing process; or the like can be used as the substrate100. In addition, a semiconductor substrate such as single crystalsilicon or a metal substrate such as a stainless substrate with aninsulating layer provided thereover is also applicable. In addition, asthe substrate 100, the large-sized substrate having the size of 320mm×400 mm, 370 mm×470 mm, 550 mm×650 mm, 600 mm×720 mm, 680 mm×880 mm,1000 mm×1200 mm, 1100 mm×1250 mm, or 1150 mm×1300 mm can be used.

It is preferable that a base layer 201 formed of a metal material suchas Ti (titanium), W (tungsten), Cr (chromium), Ta (tantalum), Ni(nickel), or Mo (molybdenum); or an oxide thereof over the substrate 100by a method such as a sputtering method or an evaporation method.Although the base layer 201 may be formed in thickness from 0.1 to 10μm, a multilayer structure is not always needed since it may be formedextremely thinly. It is noted that this base layer 201 is provided inorder to form the gate electrode layer with much adhesiveness. Whenadequate adhesiveness is obtained, the gate electrode layer may bedirectly formed over the substrate 100 by a droplet-discharging methodwithout forming the base layer 201. Moreover, atmospheric-pressureplasma treatment may be performed. Furthermore, not only before formingthe gate electrode layer but also in the case where a conductive layeris formed over an organic layer, an inorganic layer, a metal layer, andthe like by the droplet-discharging method or where the organic layer,the inorganic layer, the metal layer, and the like are formed over theconductive layer formed by the droplet-discharging method, the aboveprocess may be performed in the same way in order to improve theadhesiveness with the under layer.

A gate wiring layer 202, a gate electrode layer 203, a capacitor-wiringlayer 204, and gate electrode layers 205 are formed on the base layer201 by discharging a composition including a conductive material by adroplet-discharging method. A particle or a dispersive nanoparticle of ametal such as Ag, Au, Cu, Ni, Pt, Pd, Ir, Rh, W, Al, Ta, Mo, Cd, Zn, Fe,Ti, Si, Ge, Zr, Ba, or silver halide can be used as the conductivematerial. Moreover, ITO (alloy of indium oxide and tin oxide); ITOincluding silicon oxide; organic indium; organic tin; zinc oxide (ZnO);titanium nitride (TiN); or the like used for a transparent conductivelayer can be used. Since the gate wiring layer 202 is preferably made tohave low resistance, it is preferable to use any one of gold, silver,and copper that is dissolved or diffused in a solvent in considerationof the resistance. It is more preferable to use silver or copper, whichhas lower resistance among them. However, in the case of using silver orcopper, a barrier film may be additionally formed so as to prevent theimpurity from disparting. As the barrier layer when the copper is usedas the wiring, an insulating or conductive material including nitrogensuch as silicon nitride, silicon oxynitride, aluminum nitride, titaniumnitride, or tantalum nitride may be formed by the droplet-dischargingmethod. A solvent corresponds to esters such as butyl acetate, alcoholssuch as isopropyl alcohol, an organic solvent such as acetone, or thelike. Surface tension and viscosity are appropriately adjusted byadjusting concentration of the solution or by adding a surface-activeagent or the like.

The viscosity of the composition to be applied by thedroplet-discharging method is preferable from 5 to 20 mPa·s in order toprevent the drying of the composition and to facilitate the dischargingof the composition from the nozzle. It is preferable that the surfacetension is 40 N/m or less. The viscosity and the like of the compositionmay be adjusted appropriately in accordance with the solvent and theapplication. For example, the composition in which ITO, ITO includingsilicon oxide, organic indium, or organic tin is dissolved or diffusedin a solvent has the viscosity from 5 to 20 mPa·s, the composition inwhich the silver is dissolved or diffused in the solvent has theviscosity from 5 to 20 mPa·s, and the composition in which the gold isdissolved or diffused in the solvent has the viscosity from 10 to 20mPa·s.

Although the diameter of the particle of the conductor depends on thediameter of the nozzle or the desired pattern shape, the diameter of theparticle of the conductor is preferably small in order to prevent theclogging of the nozzle and to manufacture a minute pattern.Specifically, the diameter of the particle of the conductor ispreferably approximately 0.1 μm or less. When the composition is formedby a known method such as an electrolytic method, an atomizing method,or a wet reduction method, the size of the particle is generally in therange of approximately 0.5 to 10 μm. On the other hand, when thecomposition is formed by a gas evaporation method, each nanoparticleprotected with a dispersing agent is as small as approximately 7 nm insize. Furthermore, when a surface of each nanoparticle is covered by acoating agent, the nanoparticles in a solvent are not aggregated and areuniformly dispersed in the solvent at a room temperature, and thereforethe solvent exhibits the similar behavior to that of liquid.Accordingly, the coating agent is preferably used.

The process for discharging the composition may be performed under thereduced pressure. This is because the following process of drying andbaking can be omitted or shortened due to the volatilization of thesolvent of the composition after the composition is discharged andbefore it lands on the processing object. After discharging the droplet,one or both of drying and baking are performed under normal pressure orreduced pressure by irradiation of a laser beam, rapid thermalannealing, a heating furnace, or the like. Although both of the dryingand baking are heat treatment process, the purpose, the temperature, andthe time are different respectively. Specifically, the drying process isperformed for 3 minutes at 100° C., and the baking process is performedfor 15 to 120 minutes at 200 to 350° C. In order to perform the dryingand the baking processes well, the substrate may be heated in advance attemperatures from 100 to 800° C., preferably from 200 to 350° C. thoughit depends on the material and the like of the substrate. This processvolatilizes the solvent in the droplet or removes the diffusing agentchemically so as to cure and shrink the peripheral resin and toaccelerate the fusion and welding. The atmosphere is an oxygenicatmosphere, a nitrogenous atmosphere, or the air. However, it ispreferable to employ the oxygenic atmosphere under which the metalelement is easily decomposed or the diffused solvent is easily removed.

The laser irradiation may be performed by using a continuous wave orpulsed wave, gas laser or solid-state laser. As the gas laser, anexcimer laser and the like are given. As the solid-state laser, a laserusing a crystal such as YAG, YVO₄, GdVO₄ or the like each of which isdoped with Cr, Nd, or the like is given. It is noted that the continuouswave laser is preferable in point of the absorption ratio of the laserbeam. Moreover, a hybrid laser irradiation method in which thecontinuous wave laser is used in combination with the pulsed laser maybe used. However, when the substrate does not have enoughheat-resistance, the heat treatment by the laser irradiation ispreferably as short as several microseconds to several tens seconds. Arapid thermal annealing (RTA) method is performed in such a way that aninfrared lamp or a halogen lamp for emitting the light in the range ofan ultraviolet to infrared region is used under the inert atmosphere toincrease the temperature rapidly so that the heat can be addedinstantaneously for several microseconds to several minutes. Since thistreatment can add the heat instantaneously, substantially only a thinfilm in an upper part is heated without giving any effect on a film in alower part.

Although the gate wiring layer 202 and the capacitor-wiring layer 204are formed by the droplet-discharging method in this embodiment mode, itmay be formed by a plasma CVD method or a sputtering method.

Next, as shown in FIG. 4B, a photosensitive resin 206, which is amaterial of a resist mask, is discharged or applied over the gate wiringlayer 202, the gate electrode layer 203, the capacitor-wiring layer 204,and the gate electrode layer 205. In the case of applying thephotosensitive resin 206, a spin coater, a slit coater, or the like maybe used. As the photosensitive resin 206, a negative photosensitiveresin or a positive photosensitive resin that is photosensitive to thelight in range of an ultraviolet to infrared region is used. Thenegative photosensitive resin is used in this embodiment mode.

Next, a laser imaging system 207 is used to irradiate the photosensitiveresin 206 with a laser beam 208 and to write a pattern while moving thesubstrate or the laser.

The laser imaging system is explained with reference to FIG. 33 here. Asshown in FIG. 33, a laser imaging system 2001 includes a personalcomputer (hereinafter referred to as a PC) 2002 for executing variouscontrols when irradiating the laser beam; a laser oscillator 2003 foroutputting the laser beam, a power supply 2004 of the laser oscillator2003; an optical system (ND filter) 2005 for attenuating the laser beam;an acousto-optic modulator (AOM) 2006 for modulating the intensity ofthe laser beam; an optical system 2007 including a lens for expanding orconverging a cross section of the laser beam, a mirror for changing theoptical path of the laser beam, and the like; a substrate-movingmechanism 2009 having an X stage and a Y stage; a D/A converter 2010 fordigital/analog converting a control data output from the PC; a driver2011 for controlling the acousto-optic modulator 2006 in accordance withthe analog voltage output from the D/A converter; and a driver 2012 foroutputting a drive signal for driving the substrate-moving mechanism2009.

As the laser oscillator 2003, a laser oscillator being able to oscillateultraviolet, visible, or infrared light can be used. As the laseroscillator 2003, an excimer laser oscillator using a gas selected fromthe group consisting of KrF, ArF, KrF, XeCl, Xe, and the like; a gaslaser oscillator using a gas selected from the group consisting of He,He—Cd, Ar, He—Ne, HF, and the like; a solid-state laser oscillator usinga crystal such as YAG, GdVO₄, YVO₄, YLF, or YAlO₃ each of which is dopedwith Cr, Nd, Er, Ho, Ce, Co, Ti, or Tm; or a semiconductor laseroscillator using GaN, GaAs, GaAlAs, InGaAsP, or the like can be used.When the solid-state laser is used, it is preferable to use the secondharmonic to the fifth harmonic of the fundamental wave.

Next, a method for exposing the photosensitive material using the laserimaging system is explained. When the substrate 2008 is loaded to thesubstrate moving-mechanism 2009, the PC 2002 detects a marker formedover the substrate with the use of a camera, which is not illustrated inthe figure. Next, the PC 2002 produces motion data for moving thesubstrate-moving mechanism 2009 based on the image pattern data input inadvance and on positional data of the detected marker. Then, the amountof light emission is controlled to be the predetermined amount in such away that after the optical system 2005 attenuates the laser beam emittedfrom the laser oscillator 2003, the PC 2002 controls the acousto-opticmodulator 2006 so as to emit the predetermined amount of light. Afterthat, the optical path and the beam shape of the laser beam emitted fromthe acousto-optic modulator 2006 are changed by the optical system 2007,and then the laser beam is condensed by the lens. Then, thephotosensitive material applied over the substrate is exposed by beingirradiated with the laser beam. On this occasion, the substrate-movingmechanism 2009 moves in the X direction and the Y direction based on themotion data produced by the PC 2002. As a result, the predeterminedregion is irradiated with the laser beam, and thus the photosensitivematerial is exposed.

After being exposed, the photosensitive material is developed.Accordingly, as shown in FIG. 5A, the region irradiated with the laserbeam becomes a resist mask 209. Since the negative photosensitive resinis used here, the region irradiated with the laser beam becomes theresist mask. A part of the energy of the laser beam is converted intoheat in the resist to react a part of the resist, and therefore theresist mask becomes a little wider than the width of the laser beam. Theshorter the wavelength of the laser beam is, the shorter the beamdiameter can become when the laser beam is condensed. Therefore, it ispreferable to irradiate the laser beam having the short wavelength inorder to form the resist mask having fine width.

The beam spot on the surface of the photosensitive resin may be shapedinto a dot, circle, ellipse, rectangle, or line (a long rectangle in astrict sense) through the optical system. Although the beam spot may becircular, the linear beam spot is preferable because the linear beamspot can form the resist mask having the uniform width.

Although the case irradiating the surface of the substrate with thelaser beam is explained, the laser beam may be irradiated from a rearsurface of the substrate by changing the optical system 2007 and thesubstrate-moving mechanism 2009 and so on as appropriate.

The laser irradiation can be performed selectively by moving not onlythe substrate but also the laser beam in X-Y directions. In the lattercase, it is preferable to use a polygon mirror, a galvanometer mirror,or an acoust-optic deflector (AOD) in the optical system 2007. Moreover,the laser beam may be irradiated to the predetermined position in thesubstrate by scanning the laser beam in one of X direction and Ydirection and moving the substrate in the other one of X direction and Ydirection.

Next, the gate electrode layer 203 and the gate electrode layer 205 areetched by a known technique such as wet etching or dry etching with theuse of the resist mask 209 (FIG. 5B). Subsequently, the resist mask isremoved. Accordingly, as shown in FIG. 5C, the gate electrode layers 203and 205 having the narrow width can be formed.

Next, it is desirable to perform one of the following two processes astreatment to the base layer 201 exposed to the surface.

One process is that a part of the base layer 201 that is not overlappingthe gate wiring layer 202, the gate electrode layers 203 and 205, andthe capacitor-wiring layer 204 is insulated to form an insulating layer210 (refer to FIG. 5C). In other words, the part of the base layer 201that is not overlapping the gate wiring layer 202, the gate electrodelayer 203, the gate electrode layer 205, and the capacitor-wiring layer204 is oxidized to form an insulator. Thus, in the case of insulatingthe base layer 201 by means of oxidization, it is preferable that thebase layer 201 has a thickness from 0.1 to 10 nm in order to facilitatethe oxidization. The oxidization may be performed by a method in whichthe substrate is exposed in the atmosphere of oxygen or by heattreatment.

The other process is that the base layer 201 is etched away using thegate wiring layer 202, the gate electrode layers 203 and 205, and thecapacitor-wiring layer 204 as masks. In the case of using this process,the thickness of the base layer 201 is not limited.

Subsequently, a gate-insulating layer 211 is formed in a single-layerstructure or a multilayer structure by the plasma CVD method or thesputtering method (refer to FIG. 6A). It is particularly preferable thatthe gate-insulating layer 211 is a multilayer including three layers: aninsulating layer 212 formed of silicon nitride; an insulating layer 213formed of silicon oxide; and an insulating layer 214 formed of siliconnitride. It is noted that in order to form an insulating layer of highdensity with low gate leak current at lower film-forming temperature,the reaction gas may include a noble gas element such as Ar, and thereaction gas may be mixed into the insulating layer to be fanned. Whenthe insulating layer 212 in contact with the gate-wiring layer 202, thegate electrode layers 203 and 205, and the capacitor-wiring layer 204 isformed of silicon nitride or silicon nitride oxide, the deteriorationdue to the oxidization can be prevented. In addition, when theinsulating layer 212 in contact with the gate wiring layer 202, the gateelectrode layers 203 and 205, and the capacitor-wiring layer 204 isformed of NiB (nickel boron), the surface can be smoothed.

Next, a semiconductor layer 215 is formed. The semiconductor layer 215is formed of an AS or an SAS manufactured by a vapor growth method orthe sputtering method using a semiconductor material gas typified bysilane or germane. As the vapor growth method, the plasma-CVD method andthe thermal CVD method can be used.

When the plasma CVD method is employed, the AS is formed using a mixedgas of SiH₄ and H₂ or using a gas of SiH₄, which are the semiconductormaterial gas. When SiH₄ is diluted with H₂ by from 3 to 1000 times tomake a mixed gas or when Si₂H₆ is diluted with GeF₄ with a dilution rateof Si₂H₆:GeF₄=20 to 40:0.9, an SAS in which the composition ratio of Siis 80% or more can be obtained. In particular, the latter case ispreferable because the semiconductor layer 215 can have crystallinityfrom the interface between the semiconductor layer 215 and the baselayer.

An insulating layer 216 is formed over the semiconductor layer 215 bythe plasma CVD method or the sputtering method. As shown in thefollowing step, this insulating layer 216 is left over the semiconductorlayer 215 over the gate electrode layers 203 and 205 and serves as achannel-protective layer. Therefore, the insulating layer 216 ispreferably formed of a dense film in order to prevent the semiconductorlayer 215 from being contaminated with external impurities such as metalor an organic material and to keep an interface between the insulatinglayer 216 and the semiconductor layer 215 clean. It is preferable to usea silicon nitride film, which is formed by diluting a silicide gas withargon or the like by 100 to 500 times according to a glow-dischargingdecomposition method, because a dense silicon nitride film can be formedeven at a deposition temperature of 100° C. or less. Another insulatingfilm may be formed thereover if necessary.

It is possible to perform the processes continuously from forming thegate-insulating layer 211 up to forming the insulating layer 216 withoutexposing to the atmosphere. In other words, each interface betweenlaminated layers can be formed without being contaminated by anatmospheric constituent and a contaminated impurity element floating inthe atmosphere, and therefore variations of characteristic can bedecreased between TFTs.

Next, a mask layer 217 is formed by selectively discharging acomposition in a position over the gate electrode layers 203 and 205over the insulating layer 216 (refer to FIG. 6A). A resin material suchas an epoxy resin, an acrylic resin, a phenol resin, a novolac resin, amelamine resin, or an urethane resin is used to form the mask layer 217.In addition, the mask layer 217 may be formed by a droplet-dischargingmethod using an organic material such as benzocyclobutene, parylene,flare, or light-transmitting polyimide; a compound material made bypolymerization of siloxane-based polymer or the like; a compositionmaterial including water-soluble homopolymer and water-solublecopolymer; or the like. Alternatively, commercial resist materialincluding a photosensitizer may be used. For example, a novolac resinand naphthoquinonediazide compound that is a photosensitizer, which aretypical positive type resists; a base resin, diphenylsilane diol, anacid generation agent, and the like, which are negative type resists maybe used. In using any one of materials, the surface tension and theviscosity are appropriately adjusted by adjusting the concentration of asolvent or by adding a surface-active agent or the like.

The insulating layer 216 is etched by using the mask layer 217, and aninsulating layer 218 functioning as a channel-protective layer isformed. An n-type semiconductor layer 219 is formed over thesemiconductor layer 215 and the insulating layer 218 by removing themask layer 217. The n-type semiconductor layer 219 may be formed byusing a silane gas and a phosphine gas and can be formed of an AS or anSAS.

Next, a mask layer 220 is formed by a droplet-discharging method overthe n-type semiconductor layer 219 (refer to FIG. 6B). The n-typesemiconductor layer 219 and the semiconductor layer 215 are etched usingthis mask layer 220, and a semiconductor layer 221 and an n-typesemiconductor layer 222 are formed (refer to FIG. 6C). In this case, theTFT can be miniaturized by forming the mask layer 220 minutely in such away that the photosensitive resin is exposed using the laser beam. It isnoted that FIG. 6C schematically shows a vertical cross-sectionalstructure, and FIG. 13 shows a planar structure corresponding to A-B,C-D and E-F of FIG. 6C. Therefore, both figures may be referred tosimultaneously in this embodiment mode.

Subsequently, the mask layer 220 is removed.

Next, a through hole 223 is formed in a part of the gate-insulatinglayer 211 by an etching process, and the gate electrode layer 205 formedbelow the gate insulating layer 211 is partially exposed (refer to FIG.7A). The etching process may be performed by using a mask formed by theabove-mentioned droplet-discharging method. Plasma etching or wetetching may be applied for the etching process. The plasma etching isappropriate for processing a large-sized substrate. A fluorine-based ora chlorine-based gas such as CF₄, NF₃, Cl₂, or BCl₃ is used as anetching gas, and He or Ar may be added to the above gas appropriately.In addition, when an etching process of atmospheric pressure dischargeis applied, a local discharge process is also possible, and it is notnecessary to form a mask over the whole surface of the substrate.

Next, a solution for forming a droplet-shedding surface is discharged orapplied. As an example of the composition of the solution for formingthe droplet-shedding surface, a silane-coupling agent expressed with achemical formula: R_(n)—Si—X_((4-n)) (n=1, 2, 3) is used. It is notedthat R includes a group that is comparatively inactive, for example analkyl group. Moreover, X includes a hydrolytic group being able tocouple by means of shrinking with a hydroxyl group or adsorption waterover the surface of the substrate. Such a hydrolytic group is, forexample, halogen, a methoxy group, an ethoxy group, an acetoxy group, orthe like.

The droplet-shedding property can be enhanced by using fluorite silanecoupling agent (fluoroalkylsilane (FAS)) having a fluoroalkyl group asR, which is the typical example of the silane-coupling agent. Thefluoroalkyl group R of FAS has a structure of (CF₃)(CF₂)_(x)(CH₂)_(y)where x is not less than 0 nor more than 10 and y is not less than 0 normore than 4. When a plurality of Rs or Xs are coupled with Si, all of Rsor Xs may be the same or may be different. As typical FAS, there arefluoroalkylsilane (hereinafter referred to as FAS) such asheptadefluorotetrahydrodecyltriethoxysilane,heptadecafluorotetrahydrodecyltrichlorosilane,tridecafluorotetrahydrooctyltrichlorosilane, andtrifluoropropyltrimethoxysilane.

As the solvent of the solution for forming the droplet-shedding surface,there are a hydrocarbon-based solvent such as n-pentane, n-hexane,n-heptane, n-octane, n-decane, dicyclopentane, benzene, toluene, xylene,durene, indene, tetrahydronaphthalene, decahydronaphthalene, andsqualene; and tetrahydrofuran.

In addition, as an example of the composition of the solution forforming the droplet-shedding surface, a material having fluorine-carbonchain (fluorinated resin) can be used. As the fluorinated resin, thereare polytetrafluoroethylene (PTFE; 4-fluorinated ethylene resin),perfluoroalkoxy alkane (PFA; 4-fluorinated ethyleneperfluoroalkylvinylether copolymer resin), perfluoroethylenepropenecopolymer (PFEP; 4-fluorinated ethylene 6-fluorinated propylenecopolymer resin), ethylene-tetrafluoroethylene copolymer (ETFE;4-fluorinated ethylene-ethylene copolymer resin), polyvinylidenefluoride (PVDF; fluorinated vinylidene resin),polychlorotrifluoroethylene (PCTFE; 3-fluorinated ethylene chlorideresin), ethylene-chlorotrifluoroethylene copolymer (ECTFE; 3-fluorinatedethylene chloride-ethylene copolymer resin),polytetrafluoroethylene-perfluorodioxole copolymer (TFE/PDD), polyvinylfluoride (PVF; fluorinated vinyl resin), or the like can be used.

Subsequently, when the surface with the solution for forming thedroplet-shedding surface applied thereon is washed using ethanol, alayer forming a droplet-shedding surface 224 that is extremely thin canbe formed (refer to FIG. 7B).

Next, a laser of ultraviolet ray is irradiated from the side of the rearsurface of the substrate for the purpose of an exposure. On thisoccasion, since the gate wiring layer 202, the gate electrode layer 203,the capacitor-wiring layer 204, and the gate electrode layer 205 blockthe laser beam, the layer foaming the droplet-shedding surface 224provided over them is not exposed. As a result, the layer forming thedroplet-shedding surface 224 remains over the gate wiring layer 202, thegate electrode layer 203, the capacitor-wiring layer 204, and the gateelectrode layer 205, and the other regions become a droplet-attractingsurface. Then, a laser of ultraviolet ray is selectively irradiated fromthe side of the front surface of the substrate to the regions above thecapacitor-wiring layer 204, and one of the gate electrode layer 205. Thelayer forming the droplet-shedding surface 224 remains only necessaryparts. (refer to FIG. 7C).

In this Embodiment Mode, a method of forming the layer forming adroplet-shedding surface 224 entirely and then irradiating the laserselectively is explained, however, a method of forming the layer forminga droplet-shedding surface selectively by using one of resist mask andink-jet method or a method of forming the layer forming adroplet-shedding surface selectively and irradiating the laserselectively may be used.

Subsequently, source and drain wiring layers 225 to 229 are formed by adroplet-discharging method by selectively discharging a compositionincluding a conductive material (refer to FIG. 8A). On this occasion,since the n-type semiconductor layer 219 over the gate electrode layers203 and 205 has the droplet-shedding surface, a space 230 between thesource wiring and the drain wiring can be controlled in a self-aligningmanner.

The extremely thin film 260 having the droplet-shedding property may beremoved or may not be removed. In this embodiment mode, the extremelythin film 260 having the droplet-shedding property is removed whenetching the n-type semiconductor layer 219 in the above step.

FIGS. 8A to 8C show schematically a vertical cross-sectional structuretaken along A-B, C-D, and E-F in the plain structure of FIGS. 14 and 15.As shown in FIG. 14, a signal-wiring layer 250 extending from an end ofthe substrate 100 is formed simultaneously with a source-wiring layer225 and a drain-wiring layer 226 in such a way that the source and drainwiring layers connect electrically with the signal-wiring layer 250.Moreover, the source and drain wiring layer 226 and the gate electrodelayer 205 are electrically connected in the through hole 223 formed inthe gate-insulating layer 211. A composition mainly including a particleof metal such as Ag (silver), Au (gold), Cu (copper), W (tungsten), orAl (aluminum) can be used as a conductive material for forming thesewiring layers. Furthermore, light-transmitting indium tin oxide (ITO),organic indium including indium tin oxide and silicon oxide, organictin, zinc oxide, titanium nitride, and the like may be combined.

Next, n-type semiconductor layers 231 and 232 for forming source anddrain regions are formed by etching the n-type semiconductor layer 219over the insulating layer 218 using the source and drain wirings 225 to229 as the mask (refer to FIG. 8B).

A first electrode 233 corresponding to a pixel electrode is formed byselectively discharging a composition including a conductive material sothat it is electrically connected to the source and drain wiring layer229 (refer to FIG. 8C). It is noted that FIG. 8C schematically shows avertical cross-sectional structure taken along A-B, C-D, and E-F in aplain structure of FIG. 15, and therefore both of FIGS. 8C and 15 can bereferred to at the same time. Through the above-mentioned steps, aswitching TFT 234, a driver TFT 235, and a capacitor portion 236 areformed.

In the case of manufacturing a bottom-emission type EL display panel bythe droplet-discharging method, the first electrode 233 corresponding tothe pixel electrode may be formed in such a way that a predeterminedpattern is formed by the composition including indium tin oxide (ITO),indium tin oxide including silicon oxide (ITSO), zinc oxide, tin oxide(SnO₂), or the like and an annealing is performed thereafter.

Preferably, the first electrode 233 is formed of indium tin oxide (ITO),indium tin oxide including silicon oxide (ITSO), zinc oxide (ZnO), orthe like by a sputtering method. More preferably, indium tin oxideincluding silicon oxide is formed by a sputtering method using a targetin which silicon oxide is mixed in ITO by 2 to 10 wt %. Moreover, aconductive oxide material including silicon oxide in which zinc oxide(ZnO) is mixed in indium oxide by 2 to 20 wt % may be used. Afterforming the first electrode 233 by the sputtering method, a mask layermay be formed by the droplet-discharging method, and then the firstelectrode 233 connecting with the source and drain wiring layer 229 maybe formed by etching with the use of the mask layer. As the preferredembodiment mode of the present invention, the first electrode 233 formedof indium tin oxide including silicon oxide is formed in close contactwith the insulating layer 214 formed of silicon nitride included in thegate-insulating layer 211. According to this structure, it is possibleto obtain an advantageous effect that the proportion of the lightemitting to the outside to the light generated in the EL layer can beincreased.

In the case of the structure in which the light is emitted to the sideopposite to the substrate 100, which means a top-emission type ELdisplay panel, the composition mainly including a particle of metal suchas Ag (silver), Au (gold), Cu (copper), W (tungsten), or Al (aluminum)can be used as a material for the first electrode 233. As anothermethod, the first electrode layer may be formed in such a way that atransparent or light-reflecting conductive film is formed by thesputtering method, a mask pattern is formed thereover by thedroplet-discharging method, and then an etching process is performedthereto using the mask pattern.

Moreover, a protective layer 247 formed of silicon nitride or siliconnitride oxide and an insulating layer 248 are formed all over thesubstrate. After forming the insulating layer 248 all over the substrateby a spin coating method or a dip method, an opening is formed thereinby an etching process. The first electrode 233 and the gate-wiring layer202 are exposed by etching the protective layer 247 and thegate-insulating layer 211 under the insulating layer 248 at the sametime in this process. This etching process is not always necessary whenthe insulating layer 248 is formed by the droplet-discharging method.When the region to become the opening has the droplet-shedding surface,the opening can be formed in a self-aligning manner.

The insulating layer 248 is formed in such a way that an opening isformed in accordance with a position over the first electrode 233. Thisinsulating layer 248 can be formed of an inorganic insulating materialsuch as silicon oxide, silicon nitride, silicon oxide includingnitrogen, aluminum oxide, aluminum nitride, or aluminum oxide includingnitrogen; acrylic acid, methacrylic acid, or a derivative thereof; ahigh-molecular material having heat resistance such as polyimide,aromatic polyamide, or polybenzimidazole; inorganic siloxane including aSi—O—Si bond or an organic siloxane insulating material in whichhydrogen over the silicon is substituted by an organic group such asmethyl or phenyl among the compound made of silicon, oxygen, andhydrogen formed by using a siloxane-based material as a start material.It is preferable that the insulating layer 248 is formed of aphotosensitive material or a non-photosensitive material such as acrylicor polyimide because the opening having the cross-sectional shape whoseradius of curvature continuously changes is formed so that a thin filmin the upper layer is formed without the breakage due to the step.

Through the above-mentioned steps, a TFT substrate 200 for an EL displaypanel where a bottom gate type (also referred to as a reverselystaggered type) TFT and the first electrode are connected over thesubstrate 100 is completed.

Before forming the EL layer 237, heat treatment at 200° C. under theatmospheric pressure is performed to remove the moisture adsorbed in theinsulating layer 248 or on the surface thereof. In addition, heattreatment is performed at temperatures from 200 to 400° C., preferablyfrom 250 to 350° C. under the reduced pressure. It is preferable to formthe EL layer 237 by a vacuum evaporation method or a droplet-dischargingmethod under the reduced pressure without exposing to the atmosphere.

In addition, surface treatment may be additionally performed by exposingthe surface of the first electrode 233 to oxygen plasma or byirradiating the surface thereof with ultraviolet light. A secondelectrode 238 is formed over the EL layer 237 to form a light-emittingelement 239. This light-emitting element 239 is connected to the driverTFT 235.

Subsequently, a sealing material 240 is formed for sealing with the useof the sealing substrate 241. After that, a flexible wiring substrate250 may be connected to the gate-wiring layer 202. This is the samething to a signal-wiring layer (refer to FIG. 9).

According to the above processes, a light-emitting device having abottom-gate channel-protective type TFT can be manufactured.

Embodiment Mode 2

A method for manufacturing a bottom-gate channel-etching type TFT isexplained with reference to FIGS. 10A to 10C as the embodiment mode 2.

A composition including a conductive material is discharged over asubstrate 100 to form a gate-wiring layer 202, a gate electrode layer203, a capacitor-wiring layer 204, and a gate electrode layer 205. Next,a photosensitive resin is discharged or applied thereto, and then thephotosensitive resin is irradiated with a laser beam to form a resistmask. The gate electrode layer 203 and the gate electrode layer 205 areprocessed minutely by means of etching with the use of the resist mask.Then, the resist mask is removed. Next, the gate-insulating layer 211 isformed in a single-layer structure or a multilayer structure by theplasma CVD method or the sputtering method. It is particularlypreferable that the gate-insulating layer 211 is a multilayer includingthree layers: an insulating layer formed of silicon nitride; aninsulating layer formed of silicon oxide; and an insulating layer formedof silicon nitride. Moreover, a semiconductor layer 215 serving as anactive layer is formed. The above process is the same as that in theembodiment mode 1.

An n-type semiconductor layer 219 is formed over the semiconductor layer215 (refer to FIG. 10A). Next, a mask layer 302 is formed by dischargingthe composition selectively over the n-type semiconductor layer 219.Subsequently, the semiconductor layer 215 and the n-type semiconductorlayer 219 are etched at the same time using the mask layer 302 totransform them into an island-shape. In this case, the TFT can beminiaturized by forming the mask layer 302 minutely in such a way thatthe photosensitive resin is exposed using the laser beam.

Next, the mask layer 302 is removed.

Subsequently, after discharging or applying the solution for forming thedroplet-shedding surface, it is washed using ethanol. Then, in order touse the gate electrode layer 203 and the gate electrode layer 205 as themasks, an exposure is made from the rear surface of the substrate toform the droplet-shedding surface of the n-type semiconductor layer 219partly.

Next, the composition including the conductive material is dischargedselectively to form source and drain wiring layers 225, 226, 228, and229 by the droplet-discharging method (refer to FIG. 10B). On thisoccasion, since there is a minute droplet-shedding surface of the n-typesemiconductor layer 219 electrodes 203 and 205, a space 230 between thesource and drain wirings can be controlled minutely in a self-aligningmanner. Next, the n-type semiconductor layer 219 is etched by using thesource and drain wiring layers 225, 226, 228, and 229 as the mask toform n-type semiconductor layers 231 and 232. Since it is comparativelydifficult to etch the n-type semiconductor layer 219 and thesemiconductor layer 215 selectively, a part 303 of the semiconductorlayer 303 for forming the channel is also etched in the same process.Moreover, before this etching process, another etching process may beperformed in the same way as that in the embodiment mode 1 to form athrough hole 223 in a part of the gate-insulating layer 211 and toexpose a part of the gate electrode layer 205 positioned below thethrough hole 223. By doing this process, the source and drain wiringlayer 226 and the gate electrode layer 205 can be connected (refer toFIG. 10C).

Next, a first electrode 233 is formed in such a way that the compositionincluding the conductive material is discharged so that the firstelectrode 233 connects with the source and drain wiring layer 229electrically (refer to FIG. 10C). After that, as well as in theembodiment mode 1, a protective layer 247, an insulating layer 248, anEL layer 237, and a second electrode 238 are formed. Then, a sealingmaterial 240 is formed thereto and a sealing substrate 241 is used forsealing. Subsequently, a flexible wiring substrate 251 may be connectedto the gate-wiring layer 202.

According to the above process, the light-emitting device having thebottom-gate channel-etching type TFT can be manufactured.

It is noted that the difference between the droplet-shedding propertyand the droplet-attracting property can be expressed with the differenceof the wettability, which is the relative relation between thedroplet-shedding region and the droplet-attracting region. The regionwhere a semiconductor element is formed and the region in its vicinitywhere the semiconductor element is not formed may have the difference inthe degree of wettability to the composition including the conductivematerial. The region where the wettability is different means the regionwhere the contact angle between the surface of the region and thecomposition including the conductive material is different. The regionhaving the large contact angle to the composition including theconductive material has low wettability while the region having thesmall contact angle to the composition including the conductive materialhas high wettability. When the contact angle is large, the fluidcomposition in a liquid form does not spread on the surface of theregion and is shed from the surface, and therefore, the composition doesnot wet the surface. On the other hand, when the contact angle is small,the fluid composition spreads on the surface and wets the surface well.Therefore, the regions having the different wettability have differentsurface energy. The region having low wettability has low surface energywhile the region having high wettability has high surface energy. In thepresent invention, the difference of the contact angle between theregions having the different wettability may be 30° or more, preferably40° or more.

Embodiment Mode 3

A method for manufacturing a bottom-gate channel-protective TFT isexplained as the embodiment mode 3.

FIG. 47A shows a process for forming a gate electrode layer and agate-wiring layer connected to the gate electrode layer over a substrate3100. It is noted that FIG. 47A shows schematically a cross-sectionalstructure and FIG. 56 shows its plain structure corresponding to linesA-B and C-D in FIG. 47A. Therefore, both figures may be referred to atthe same time.

A glass substrate made of a non-alkali glass manufactured by a fusionmethod or a float method, for example, a barium borosilicate glass, analumina borosilicate glass, or an aluminosilicate glass; a ceramicsubstrate; a plastic substrate that can resist the heat in themanufacturing process; or the like can be used as the substrate 3100. Inaddition, a semiconductor substrate such as single-crystal silicon or ametal substrate such as a stainless substrate with an insulating layerformed over its surface may be applied. The substrate 3100 may have alarge size, for example 320 mm×400 mm, 370 mm×470 mm, 550 mm×650 min,600 mm×720 mm, 680 mm×880 mm, 1000 mm×1200 mm, 1100 mm×1250 mm, or 1150mm×1300 mm.

A base layer 3201 formed of a metal selected from the group consistingof Ti (titanium), W (tungsten), Cr (chromium), Ta (tantalum), Ni(nickel), and Mo (molybdenum) or formed of the oxide thereof ispreferably formed over the substrate 3100 by a method such as thesputtering method or the evaporation method. The base layer 3201 may beformed in thickness from 0.1 to 10 nm. Since the base layer is formedvery thinly, the base layer does not always need to have a multilayerstructure. The base layer 3201 is provided in order to form the gateelectrode layer with sufficient adhesiveness. Therefore, a gateelectrode layer may be formed over the substrate 3100 by thedroplet-discharging method without forming the base layer 3200 when thesufficient adhesiveness can be obtained. Instead of thedroplet-discharging method, an atmospheric plasma process may beperformed. Moreover, in the case of forming the conductive layer by thedroplet-discharging method over the organic layer, the inorganic layer,and the metal layer or in the case of forming the organic layer, theinorganic layer, the metal layer over the conductive layer formed by thedroplet-discharging method, the same process may be performed in orderto increase the adhesiveness with the under layer.

The gate wiring layer 3202, the gate electrode layer 3203, and thecapacitor-wiring layer 3204 are formed over the base layer 3201 bydischarging the composition including the conductive material accordingto the droplet-discharging method. As the conductive material forforming these layers, a metal selected from the group consisting of Ag,Au, Cu, N Pt, Pd, Ir, Rh, W, Al, Ta, Mo, Cd, Zn, Fe, Ti, Si, Ge; Zr, Ba,and the like; an alloy made of the above elements; a microparticle ofsilver halide; or a dispersive nanoparticle can be used. Moreover, ITO(alloy of indium oxide and tin oxide) used as a transparent conductivefilm, ITO including silicon oxide, organic indium, organic tin, zincoxide (ZnO), titanium nitride (TiN), or the like can be also used.Particularly, since the gate electrode layer preferably has lowresistance, it is preferable to use a solution in which any one of gold,silver, and copper is dissolved or diffused in consideration of theresistivity, and it is more preferable to use silver or copper havinglower resistance. However, as a measure against the impurity, a barrierlayer may be formed in combination. In the case of using the copper asthe wiring, the barrier layer may be formed of an insulating orconductive material including nitrogen such as silicon nitride, siliconoxynitride, aluminum nitride, titanium nitride, or tantalum nitride bythe droplet-discharging method. The solvent may be an organic solvent:esters such as butyl acetate; alcohols such as isopropyl alcohol; oracetone. The surface tension and the viscosity are adjusted asappropriate by adjusting the concentration of the solvent or by addingan surface-active agent or the like.

The viscosity of the composition applied by the droplet-dischargingmethod is preferably 5 mPa·s and more and 20 mPa or less in order toprevent the composition from drying and to discharge the compositionsmoothly from the nozzle. The surface tension is preferably 40 N/m orless. The viscosity of the composition may be adjusted appropriately inaccordance with the solvent to be used or the intended purpose. As anexample, the viscosity of the composition in which ITO, ITO includingsilicon oxide, organic indium, or organic tin is dissolved or diffusedin the solvent is in the range of 5 to 20 mPa·s, and the viscosity ofthe composition in which gold is dissolved or diffused in the solvent isin the range of 10 to 20 mPa·s.

Although the diameter of the particle of the conductor depends on thediameter of the nozzle or the desired pattern shape, the diameter of theparticle of the conductor is preferably small in order to prevent theclogging of the nozzle and to manufacture a miniature pattern.Specifically, the diameter of the particle of the conductor ispreferably approximately 0.1 μm or less. The composition is formed by aknown method such as an electrolytic method, an atomize method, or a wetreducing method. The size of the particle is generally in the range ofapproximately 0.5 to 10 μm. However, when the composition is made by agas evaporation method, each nanoparticle protected with a dispersingagent is as minute as approximately 7 nm in size. Furthermore, when asurface of each nanoparticle is covered by a coating agent, thenanoparticles in a solvent are not aggregated to each other and areuniformly dispersed in the solvent at a room temperature, therebyexhibiting behavior similar to that of aqueous fluid. As a result, thecoating agent is preferably used.

The process for discharging the composition may be performed under thereduced pressure. This is because the following process of drying andbaking can be omitted or shortened due to the volatilization of thesolvent of the composition after the composition is discharged andbefore it lands on the processing object. After discharging the solvent,one or both of drying and baking are performed under normal pressure orreduced pressure by the irradiation of a laser beam, rapid thermalannealing, a heating furnace, or the like. Although both of the dryingand baking require heat treatment, the purpose, the temperature, and thetime are different respectively. Specifically, the drying process isperformed for 3 minutes at 100° C., and the baking process is performedfor 15 to 120 minutes at 200 to 350° C. In order to perform the dryingand baking processes well, the substrate may be heated in advance attemperatures from 100 to 800° C., preferably from 200 to 350° C., thoughit depends on the material and the like of the substrate. This processvolatilizes the solvent in the solution or removes the diffusing agentchemically so as to cure and shrink the peripheral resin and toaccelerate the fusion and welding. The atmosphere may be an oxygenicatmosphere, a nitrogenous atmosphere, or the air. However, it ispreferable to employ the oxygenic atmosphere under which the metalelement is easily decomposed or the diffused solvent is easily removed.

The laser irradiation may be performed using a continuous wave or pulsedgas laser or using a continuous wave or pulsed solid-state laser. As thegas laser, an excimer laser and the like are given. As the solid-statelaser, a laser using a crystal such as YAG, YVO₄, GdVO₄, or the likeeach of which is doped with Cr, Nd, or the like is given. It is notedthat the continuous wave laser is preferable in point of the absorptionratio of the laser beam. Moreover, a hybrid laser irradiation method inwhich the continuous wave laser is used in combination with the pulsedlaser may be used. However, in consideration of the heat resistance ofthe substrate, the heat treatment by the laser irradiation is preferablyas short as several microseconds to several tens seconds. Rapid thermalannealing (RTA) is performed in such a way that an infrared lamp or ahalogen lamp for emitting the light in the range of an ultraviolet toinfrared region is used under the inert atmosphere to increase thetemperature rapidly so that the heat can be added instantaneously forseveral microseconds to several minutes. Since this treatment can addthe heat instantaneously, substantially only a thin film in an upperpart is heated without giving any effect on a film in a lower part.

Although the gate wiring layer and the capacitor-wiring layer are formedby the droplet-discharging method in this embodiment mode, it may beformed by a plasma CVD method or a sputtering method.

Next, as shown in FIG. 47B, a photosensitive resin 3205 is discharged orapplied over the gate wiring layer 3202, the gate electrode layer 3203,and the capacitor-wiring layer 3204. In the case of applying thephotosensitive resin 3205, a spin coater, a slit coater, or the like maybe used. The photosensitive resin may be a negative photosensitive resinor a positive photosensitive resin, both of which are the materialsensitive to the light in the range of an ultraviolet to infraredregion.

Next, the photosensitive resin 3205 is irradiated with a laser beam 3207using a laser imaging system 3206 by which a pattern is written whilemoving the substrate or the laser beam (FIG. 47C).

As a result, a predetermined position is irradiated with the laser beam.Thus, the photosensitive material is exposed and developed, and a resistmask 3208 is formed in the region irradiated with the laser beam that isindicated in FIG. 48A. Here, since the negative photosensitive resin isused, the region irradiated with the laser beam becomes the resist mask.Since a part of the energy of the laser beam is changed into heat in theresist to react a part of the resist, the width of the resist maskbecomes a little larger than the width of the laser beam. Moreover, theshorter the wavelength of the laser beam is, the shorter the beamdiameter can become when the laser beam is condensed. Therefore, it ispreferable to irradiate the laser beam having the short wavelength inorder to form the resist mask having fine width.

The beam spot on the surface of the photosensitive resin 3205 is shapedinto a dot, circle, ellipse, rectangle, or line (a long rectangle in astrict sense) through the optical system. Although the beam spot may becircular, the linear beam spot is preferable because it can form theresist mask having the uniform width.

Next, the gate electrode layer 3203 is etched by a known method such asa dry etching method or a wet etching method using the resist mask 3208(FIG. 48B). As a result, the gate electrode layer 3203 having a narrowwidth can be formed as shown in FIG. 48C.

Next, it is desirable to perform one of the following two processes astreatment to the base layer 3201 exposed to the surface.

One process is that the base layer 3201 not overlapping the gate wiringlayer 3202, the gate electrode layer 3203, and the capacitor-wiringlayer 3204 is insulated to form an insulating layer 3209 (refer to FIG.48C). In other words, the base layer 3201 not overlapping the gatewiring layer 3202, the gate electrode layer 3203, and thecapacitor-wiring layer 3204 is oxidized so as to be insulated. Thus, inthe case of insulating the base layer 3201 by means of oxidization, itis preferable that the base layer 3201 has a thickness from 0.1 to 10 nmin order to facilitate the oxidization. The oxidization may be performedby a method in which the substrate is exposed in the atmosphere ofoxygen or by heat treatment.

The other process is that the base layer 3201 is etched away using thegate wiring layer 3202, the gate electrode layer 3203, and thecapacitor-wiring layer 3204 as a mask. In the case of using thisprocess, the thickness of the base layer 3201 is not limited.

Subsequently, a gate-insulating layer 3210 is formed in a single-layerstructure or a multilayer structure by the plasma CVD method or thesputtering method (refer to FIG. 49A). It is particularly preferablethat the gate-insulating layer is a multilayer including three layers:an insulating layer 3211 formed of silicon nitride; an insulating layer3212 formed of silicon oxide; and an insulating layer 3213 formed ofsilicon nitride. It is noted that in order to form an insulating layerof high density with low gate leak current at lower film-formingtemperature, the reaction gas may include a noble gas element such as Arand may be mixed into the insulating layer to be formed. By forming afirst layer using silicon nitride or silicon nitride oxide in contactwith the gate wiring layer 3202, the gate electrode layer 3203, and thecapacitor-wiring layer 3204, the deterioration due to the oxidizationcan be prevented. In addition, when the first layer in contact with thegate wiring layer 3202, the gate electrode layer 3203, and thecapacitor-wiring layer 3204 is formed of NiB (nickel boron) the surfacecan be smoothed.

Next, a semiconductor layer 3214 is formed. The semiconductor layer 3214is formed of an AS or an SAS manufactured by a vapor deposition growthmethod or the sputtering method using a semiconductor material gastypified by silane or germane. As the vapor deposition growth method,the plasma-CVD method and the thermal CVD method can be used.

When the plasma CVD method is employed, the AS is formed using a mixedgas of SiH₄ and H₂ or using a gas of SiH₄, which are the semiconductormaterial gas. When SiH₄ is diluted with H₂ by from 3 to 1000 times tomake a mixed gas or when Si₂H₆ is diluted with GeF₄ so that a gas flowrate of Si₂H₆ to GeF₄ is 20 to 40 to 0.9, an SAS in which Si compositionratio is 80% or more can be obtained. In particular, the latter case ispreferable because the semiconductor layer 3214 can have crystallinityfrom the interface between the semiconductor layer 3214 and the baselayer.

An insulating layer 3215 is formed over the semiconductor layer 3214 bythe plasma CVD method or the sputtering method. As shown in thefollowing step, this insulating layer 3215 is left over thesemiconductor layer 3214 over the gate electrode layer and serves as achannel-protective layer. Therefore, the insulating layer 3215 ispreferably formed of a dense film in order to prevent the semiconductorlayer 3214 from being contaminated with external impurities such asmetal or an organic material by keeping an interface between theinsulating layer 3215 and the semiconductor layer 3214 clean. It ispreferable to use a silicon nitride film, which is formed by diluting asilicide gas by 100 to 500 times with argon or the like by aglow-discharging decomposition method, because the dense film can beformed even at a film-forming temperature of 100° C. or less. Anotherinsulating film may be formed thereover if necessary.

It is possible to form the gate-insulating layer 3210 continuously up tothe insulating layer 3215 without exposing to the atmosphere. In thiscase, each interface between laminated layers can be formed withoutbeing contaminated by an atmospheric constituent and an airbornecontaminated impurity element in an atmosphere, and therefore variationsin properties of a TFT can be decreased.

Next, a mask layer 3216 is formed by selectively discharging acomposition at a position to over the gate electrode 3203 over theinsulating layer 3215 (refer to FIG. 49A). A resin material such as anepoxy resin, an acrylic resin, a phenol resin, a novolac resin, anacrylic resin, a melamine resin, or an urethane resin is used to formthe mask layer 3216. In addition, the mask layer 217 may be formed by adroplet-discharging method using an organic material such asbenzocyclobutene, parylene, flare, or light-transmitting polyimide; acompound material made of polymerization such as siloxane-based polymer;a composition material including water-soluble homopolymer andwater-soluble copolymer; or the like. Alternatively, a commercial resistmaterial including a photosensitizer may be used. For example, a novolacresin and naphthoquinonediazide compound that is a photosensitizer,which are typical positive type resists; a base resin, which is anegative type resist; an acid generation agent such as diphenylsilanediol; or the like may be used. In using any one of materials, surfacetension and viscosity are appropriately adjusted by diluting density ofa solution or by adding a surface-active agent or the like.

The insulating layer 3215 is etched by using the mask layer 3216, and aninsulating layer 3217 functioning as a channel-protective layer isformed. An n-type semiconductor layer 3218 is formed over thesemiconductor layer 3214 and the insulating layer 3217 by removing themask layer 3216. The n-type semiconductor layer 3218 may be formed byusing a silane gas and a phosphine gas and can be formed of an AS or anSAS.

Next, a mask layer 3219 is formed by a droplet-discharging method overthe n-type semiconductor layer 3218. By using this mask layer 3219, then-type semiconductor layer 3218 and the semiconductor layer 3214 areetched, and a semiconductor layer 3220 and an n-type semiconductor layer3221 are formed (refer to FIG. 49C). In this case, the TFT can beminiaturized by forming the mask layer 3219 microscopically in such away that the photosensitive resin is exposed by the laser beam. It isnoted that FIG. 49C schematically shows a vertical sectional structure,and FIG. 13 shows a planar structure corresponding to A-B and C-Dthereof.

Subsequently, the mask layer 3219 is removed.

Next, a solution for forming a droplet-shedding surface is discharged orapplied (FIG. 50A). As an example of the composition of the solution forforming the droplet-shedding surface, a silane-coupling agent expressedwith a chemical formula: R_(n)—Si—X_((4-n)) (n=1, 2, 3) is used. It isnoted that R includes a group that is comparatively inactive, forexample an alkyl group. Moreover, X includes a hydrolytic group beingable to couple by means of shrinking with a hydroxyl group or adsorptionwater on the surface of the substrate. Such a hydrolytic group is forexample, halogen, a methoxy group, an ethoxy group, an acetoxy group, orthe like.

The droplet-shedding property can be enhanced by using a fluorite silanecoupling agent (fluoalkylsilane (FAS)) having fluoalkyl in R, which isthe typical example of the silane-coupling agent. R of FAS has astructure of (CF₃)(CF₂)_(x)(CH₂)_(y) where x is not less than 0 nor morethan 10 and y is not less than 0 nor more than 4. When a plurality of Rsor Xs are coupled with Si, all of Rs and Xs may be the same or may bedifferent. As typical FAS, there are fluoroalkylsilane (hereinafterreferred to as FAS) such as heptadefluorotetrahydrodecyltriethoxysilane,heptadecafluorotetrahydrodecyltrichlorosilane,tridecafluorotetrahydrooctyltrichlorosilane, andtrifluoropropyltrimethoxysilane.

As the solvent of the solution for forming the droplet-shedding surface,there are hydrocarbon-based solvent such as n-pentane, n-hexan,n-heptane, n-octane, n-decane, dicyclopentane, benzene, toluene, xylene,durene, indene, tetrahydronaphthalene, decahydronaphthalene, orsqualene; or tetrahydrofuran.

In addition, as an example of the composition of the solution forforming the droplet-shedding surface, a material having fluorine-carbonchain (fluorinated resin) can be used. As the fluorinated resin, thereare polytetrafluoroethylene (PTFE; 4-fluorinated ethylene resin),perfluoroalkoxy alkane (PFA; 4-fluorinated ethyleneperfluoroalkylvinylether copolymer resin), perfluoroethylenepropenecopolymer (PFEP; 4-fluorinated ethylene 6-fluorinated propylenecopolymer resin), ethylene-tetrafluoroethylene copolymer (ETFE;4-fluorinated ethylene-ethylene copolymer resin), polyvinylidenefluoride (PVDF; fluorinated vinylidene resin),polychlorotrifluoroethylene (PCTFE; 3-fluorinated ethylene chlorideresin), ethylene-chlorotrifluoroethylene copolymer (ECTFE; 3-fluorinatedethylene chloride-ethylene copolymer resin),polytetrafluoroethylene-perfluorodioxole copolymer (TFE/PDD), polyvinylfluoride (PVF; fluorinated vinyl resin), or the like can be used.

Subsequently, when the surface with the solution for forming thedroplet-shedding surface applied thereon is washed using ethanol, alayer forming a droplet-shedding surface 3222 that is extremely thin canbe formed.

Next, a laser of ultraviolet ray or the like is irradiated from the sideof the rear surface of the substrate. On this occasion, since thegate-wiring layer 3202, the gate electrode layer 3203, and thecapacitor-wiring layer 3204 block the laser beam, the layer forming thedroplet-shedding surface provided over them is not irradiated. As aresult, the droplet-shedding surface of the n-type semiconductor layer3218 is formed only over the gate electrode layer 3203, and the otherregions of the n-type semiconductor layer 3218 become adroplet-attracting surface (refer to FIG. 50B).

Subsequently, source and drain wiring layers 3225 and 3226 are formed bya droplet-discharging method by selectively discharging a compositionincluding a conductive material (refer to FIG. 50C). On this occasion,since an extremely thin film 3223 having the droplet-shedding propertyexists over the gate electrode layer 3203, a space 3224 between thesource wiring and the drain wiring can be controlled in a self-aligningmanner.

The extremely thin film 3223 having the droplet-shedding property may beremoved or may not be removed. In this embodiment mode, the extremelythin film 3223 having the droplet-shedding property is removed whenetching the n-type semiconductor layer 3218 in the following step.

FIG. 51A shows a vertical cross-sectional structure and FIG. 58 shows aplain structure corresponding to A-B and C-D of FIG. 51A. As shown inFIG. 58, a signal-wiring layer 3250 is formed simultaneously with thesource and drain wiring layers 3225 and 3226 so that the signal-wiringlayer 3250 is connected with the source and drain wiring layers 3225 and3226 electrically. As the conductive material for forming these wiringlayers, a composition mainly including a particle of a metal selectedfrom the group consisting of Ag (silver), Au (gold), Cu (copper), W(tungsten), Al (aluminum), and the like can be used. Moreover,light-transmitting indium tin oxide (ITO), organic indium includingindium tin oxide and silicon oxide, organic tin, zinc oxide, titaniumnitride, and the like may be combined.

Next, the n-type semiconductor layer 3221 over the insulating layer 3217is etched using the source and drain wiring layers 3225 and 3226 asmasks to form n-type semiconductor layers 3227 and 3228 for formingsource and drain regions (refer to FIG. 51A).

A pixel electrode layer 3229 is formed by discharging a compositionincluding a conductive material so as to connect with the source anddrain wiring layer 3226 electrically (refer to FIG. 51B). In the case ofmanufacturing a transmission-type liquid crystal display panel, thepixel electrode layer 3229 may be formed in such a way that apredetermined pattern is formed using a composition including indium tinoxide (ITO), indium tin oxide including silicon oxide, zinc oxide (ZnO),tin oxide (SnO₂), or the like and the pattern is baked. In the case ofmanufacturing a reflection-type liquid crystal display panel, acomposition mainly including a particle of metal such as Ag (silver), Au(gold), Cu (copper), W (tungsten), Al (aluminum), or the like can beused. As another method, the pixel electrode layer may be formed in sucha way that a transparent or light-reflecting conductive film is formedby the sputtering method, a mask pattern is formed by thedroplet-discharging method, and then the etching is performed using themask pattern. It is noted that FIG. 51B schematically shows a verticalcross-sectional structure, and FIG. 59 shows a plain structurecorresponding to A-B and C-D of FIG. 51B. Therefore, both figures may bereferred to at the same time.

According to the above process, a TFT substrate 3200 for aliquid-crystal display panel in which a bottom-gate type (also referredto as a reversely staggered type) TFT is connected with the pixelelectrode over the substrate 3100 is obtained.

Next, an insulating layer 3230, which is called an orientation film, isformed over the pixel electrode layer 3229 by a printing method or aspin-coating method. It is noted that the insulating layer 3230 can beformed selectively as being illustrated in the figure by ascreen-printing method or an offset-printing method. After that, arubbing is performed. Subsequently, a sealing material 3231 is formed inthe peripheral region of the pixel by the droplet-discharging method(refer to FIG. 51C).

After that, an opposing substrate 3234 over which the insulating layer3232 functioning as the orientation film and the conductive layer 3233functioning as the opposing electrode is pasted to the TFT substrate3200 with the spacer interposed therebetween. Then, a liquid crystallayer 3350 is provided in its space, and the liquid crystal displaypanel can be thus manufactured (FIG. 52A). A filler may be mixed in thesealant 3231, and a color filter or a shielding film (such as a blackmatrix) may be formed to the opposing substrate 3234. As the method forforming the liquid crystal layer 3350, a dispensing system (droppingsystem) or a dip system (drawing system) in which a liquid crystal isinjected using capillary phenomenon after pasting the opposing substrate3234 can be used.

According to the liquid crystal injection method using the dispensingsystem, the sealing material 3231 is used to form a closed loop intowhich the liquid crystal is dripped once or multiple times.Subsequently, the substrates are pasted in vacuum, and then ultravioletray curing is performed to have the space between the substrates filledwith the liquid crystal.

Next, the insulating layers 3211 to 3213, which are indicated by aregion 3235, are removed by means of ashing with the use of oxygen gasunder the atmospheric pressure or near-atmospheric pressure. Thisprocess uses oxygen gas and one or a plurality of gases selected fromthe group consisting of hydrogen, CF₄, NF₃, H₂O, and CHF₃. In thisprocess, the ashing process is performed after sealing with the use ofthe opposing substrate in order to prevent the damage or breakdown dueto the electrostatic. However, the ashing process may be performedanytime when the effect due to the electrostatic is small.

Subsequently, a connection terminal 3236 for connection is provided insuch a way that the gate-wiring layer 3202 is electrically connectedthrough an anisotropic conductive layer. The connection terminal 3236translates the signal or the potential from the outside. The aboveprocess completes a liquid crystal display panel including achannel-protective switching TFT 3237 and a capacitor element 3238. Thecapacitor element 3238 is formed of the capacitor-wiring layer 3204, thegate-insulating layer 3210, and the pixel electrode layer 3229.

According to the above process, the liquid-crystal display device havingthe bottom-gate channel-protective type TFT can be manufactured.

Embodiment Mode 4

The embodiment mode 3 showed the structure in which the pixel electrodelayer 3229 is in a direct contact with the source and drain wiring layer3226. An example in which an insulating layer may be interposedtherebetween is shown as another embodiment mode in this EmbodimentMode.

After completing the processes up to the process of FIG. 51A similarlyas Embodiment Mode 3, an insulating layer 3239 functioning as theprotective film is formed (refer to FIG. 53A). A film of silicon nitrideor silicon oxide formed by the sputtering method or the plasma CVDmethod may be applied as this protective film. An opening 3240 is formedin the insulating layer 3239 in order to connect the source and drainwiring layer 3226 with the pixel electrode layer 3229 electricallythrough the opening 3240 (refer to FIG. 53B). Another opening 3241required to paste the connection terminal afterward may be formedsimultaneously as the opening 3240.

The way to form the openings 3240 and 3241 is not limited in particular.For example, the openings can be formed selectively by the plasmaetching under the atmospheric pressure or can be formed by a wet etchingprocess after forming a mask according to the droplet-dischargingmethod. When the insulating layer 3239 is an inorganic siloxane film oran organic siloxane film formed by the droplet-discharging method, theprocess for forming the opening can be omitted. Moreover, when theregion where the opening is formed is made to have a droplet-sheddingsurface, it is possible to form the opening in a self-aligning manner.

After conducting following manufacturing steps similarly as EmbodimentMode 3, the liquid crystal display panel with a bottom-gatechannel-protective type switching TFT 3237 and a capacitor element 3238shown in FIG. 53 is completed.

Embodiment Mode 5

A method for manufacturing a channel-etching type TFT is explained asthe embodiment mode 5 with reference to FIGS. 54A to 54C and 55.

A gate-wiring layer 3202, a gate electrode layer 3203, and acapacitor-wiring layer 3204 are formed over a substrate 3100 bydischarging a composition including a conductive material according to adroplet-discharging method. Next, after discharging or applying aphotosensitive resin, the photosensitive resin 3205 is irradiated with alaser beam and developed, and thus a resist mask is formed. The etchingis performed using the resist mask 3208 to process the gate electrodelayer 3203 minutely, and then the resist mask 3208 is removed. Next, thegate-insulating layer 3210 is formed in a single-layer or multilayerstructure by means of a plasma CVD method or a sputtering method. It isparticularly preferable that the gate-insulating layer is the multilayerincluding three layers: an insulating layer 3211 formed of siliconnitride; an insulating layer 3212 formed of silicon oxide; and aninsulating layer 3213 formed of silicon nitride. Moreover, asemiconductor layer 3214 functioning as the active layer is formed. Theabove process is the same as that in the embodiment mode 1.

An n-type semiconductor layer 3218 is formed onr the semiconductor layer3214 (refer to FIG. 54A). Next, a mask layer 3302 is formed bydischarging the composition selectively on the n-type semiconductorlayer 3218. Subsequently, the semiconductor layer 3214 and the n-typesemiconductor layer 3218 are etched simultaneously using the mask layer3302 to transform them into an island-shape. In this case, the TFT isminiaturized by forming the mask layer 3302 minutely in such a way thatthe photoresist is exposed with the laser beam. After that, the masklayer 3302 is removed.

Subsequently, after discharging or applying the solution for forming thedroplet-shedding surface, it is washed using ethanol. Then, in order touse the gate-wiring layer 3202, the gate electrode layer 3203, and thecapacitor-wiring layer 3204 as the masks, an irradiation of light ismade from the rear surface of the substrate to form a droplet-attractingsurface from a part of the droplet-shedding surface and.

Next, the composition including the conductive material is dischargedselectively to form source and drain wiring layers 3225 and 3226 by thedroplet-discharging method (refer to FIG. 54B). On this occasion, sincethere is a minute droplet-shedding surface over the gate electrode layer3203, a space 3224 between the source and drain wirings can becontrolled minutely in a self-aligning manner. Next, the n-typesemiconductor layer 3218 is etched by using these wiring layers as themasks to form n-type semiconductor layers 3227 and 3228. Since it isdifficult to etch an n-type semiconductor layer 3220 and a semiconductorlayer 3221 selectively, a part 3303 of the semiconductor layer 3221 forforming the channel forming region is also etched partially in the sameprocess. Subsequently, a pixel electrode 3229 is formed by dischargingthe composition including the conductive material so that the pixelelectrode 3229 is connected electrically with the source and drainwiring layer 3226 (refer to FIG. 54C).

Next, an insulating layer 3230 functioning as an orientation film isformed. Subsequently, a sealing material 3231 is formed by which thesubstrate 3100 is pasted to an opposing substrate 3234 over which anconductive layer 3233 functioning as an opposing electrode and aninsulating layer 3232 functioning as the orientation film are formed.Then, a liquid crystal layer 3350 is provided between the substrate 3100and the opposing substrate 3234. Next, a region to which a connectionterminal is pasted is exposed by means of etching under the atmosphericpressure or near-atmospheric pressure, and a flexible wiring substrate3236 is pasted to a connection terminal. Thus, a liquid crystal displaypanel having a display function can be manufactured (refer to FIG. 55).

Embodiment Mode 6

This embodiment mode explains the case of forming a scanning line drivercircuit over a substrate 100 as shown in FIG. 3 by forming thesemiconductor layer using an SAS in the EL display panel or theliquid-crystal display panel manufactured according to any one of theembodiment modes 1 to 5.

FIG. 24 shows a block diagram of the scanning line driver circuitincluding the n-channel TFT using the SAS in which the electric-fieldmobility in the range of 1 to 15 cm²/V·sec is obtained.

In FIG. 24, a block corresponds to a pulse output circuit 800 foroutputting a sampling pulse of one line and a shift resistor includes nnumber of pulse output circuits. A pixel 802 (corresponding to the pixel102 in FIG. 3) is connected to an end of a buffer circuit 801.

FIG. 25 shows a specific structure of a pulse output circuit 800including n-channel TFTs 601 to 613. On this occasion, the size of theTFT may be determined in consideration of the operating characteristicof the n-channel TFT using the SAS. For example, when the channel lengthis set to 8 μm, the channel width can be set in the range of 10 to 80μm.

FIG. 26 shows a specific structure of the buffer circuit 801. In thesame way, the buffer circuit in this figure also includes n-channel TFTs620 to 635. On this occasion, the size of the TFT may be determined inconsideration of the operating characteristic of the n-channel TFT usingthe SAS. For example, when the channel length is set to 10 μm, thechannel width can be set in the range of 10 to 1800 μm.

In the case of manufacturing an EL display panel, in order to achievesuch a circuit, it is necessary to connect the respective TFTs withwirings. FIG. 16 shows the structure of the wirings in such a case. Aswell as in the embodiment mode 1, FIG. 16 shows a gate electrode layer203, a gate-insulating layer 211 (a multilayer including three layers:an insulating layer 212 formed of silicon nitride; an insulating layer213 formed of silicon oxide; and an insulating layer 214 formed ofsilicon nitride), an n-type semiconductor layer 215 formed of an SAS,and n-type semiconductor layers 231 and 232 for forming source and drainwiring layers 225 and 226. In this case, connection-wiring layers 270,271, and 272 are formed over the substrate 100 in the same process forforming the gate electrode layer 203. Then, the TFTs are connectedappropriately with the use of source and drain wiring layers 225 and 226and a connection wiring layer 273 formed in the same process for formingthe source and drain wiring layers 225 and 226 performed by etching apart of the gate-insulating layer so as to expose the connection wiringlayers 270, 271, and 272. Thus, various circuits are achieved.

On the other hand, in order to achieve such a circuit in the liquidcrystal display panel, it is also necessary to connect the respectiveTFTs with wirings. FIG. 11 shows an example of the structure of thewiring in such a case. As well as in the embodiment mode 3, FIG. 11shows a gate electrode layer 3203, a gate-insulating layer 3210 (amultilayer including three layers: an insulating layer 3211 forted ofsilicon nitride; an insulating layer 3212 formed of silicon oxide; andan insulating layer 3213 formed of silicon nitride), an n-typesemiconductor layer 3214 formed of an SAS, n-type semiconductor layers3227 and 3228 for forming a source and a drain, and source and drainwiring layers 3225 and 3226. In this case, connection-wiring layers3270, 3271, and 3272 are formed over the substrate 3100 in the sameprocess for forming the gate electrode layer 3203. Then, the TFTs areconnected appropriately with the use of the source and drain wiringlayers 3225 and 3226 and a connection-wiring layer 3273 formed throughthe same process for forming the source and drain wiring layers 3225 and3226 performed by etching a part of the gate-insulating layer so as toexpose the connection-wiring layers 3270, 3271, and 3272. Thus, variouscircuits are achieved.

Embodiment Mode 7

A top-gate TFT is explained with reference to FIG. 28 and FIGS. 34A to36B as the embodiment mode 7.

A base layer 201 is foamed over a substrate 100 by means of a sputteringmethod or an evaporation method. A solution for forming adroplet-shedding surface is discharged or applied to the base layer 201(refer to FIG. 34A). Subsequently, an extremely thin film 120 beingsuperior in the droplet-shedding property can be formed by using ethanolto wash the surface with the solution for forming the droplet-sheddingsurface applied thereon.

Next, a droplet-attracting surface is formed by irradiating a laser beam208 to a part of the droplet-shedding surface 121 using a laser imagingsystem 207 while moving the substrate or the laser (refer to FIG. 34B).Moreover, contrary to this embodiment mode, another method may beemployed to make the irradiated region have the droplet-shedding surfaceby irradiating a part of the droplet-attracting surface with the use ofthe laser beam.

Next, source and drain wiring layers 122 to 125 are formed by adroplet-discharging method in such a way that a composition including aconductive material is discharged so as to sandwich the droplet-sheddingsurface 121 (refer to FIG. 35A). On this occasion, since there is thedroplet-shedding surface 121, a space 230 between the source and drainwirings can be controlled minutely in a self-aligning manner.Subsequently, the base layer 201 is insulated. On this occasion, theextremely thin film having the droplet-shedding property 120 may beremoved or may not be removed. Moreover, the extremely thin film havingthe droplet-shedding property 120 can be removed at the same time asinsulating the base layer.

Next, regions 126 to 129 with phosphorous doped is formed selectivelyover the source and drain wiring layers 122 to 125 by the plasmaimmersion method.

The region where the phosphorous is doped reacts with a part of thesemiconductor layer to be formed afterward, and n-type semiconductorlayers 126 a to 129 a are formed as shown in FIG. 36A.

The plasma immersiong method is a method for doping selectively only thesurface of the source and drain wiring layer by RF glow dischargingwhile flowing a phosphine gas or the like with the use of a P-CVDapparatus or the like.

Next, an AS or an SAS is formed by a vapor growth method such as aplasma CVD method or a sputtering method. In the case of using theplasma CVD method, the AS is formed using SiH₄ or a mixed gas of SiH₄and H₂, which are the semiconductor material gas. The SAS is formedusing the mixed gas in which SiH₄ is diluted with H₂ by 3 to 1000 times.When the SAS is formed using these kind of gas, the crystallinity issuperior in the upper part of the semiconductor layer to the lower partthereof, and therefore, the combination with the top-gate TFT in whichthe gate electrode is formed over the upper layer of the semiconductorlayer is appropriate.

The semiconductor layer 130 is formed in the position corresponding tothe source and drain wiring layers 122 to 125 using a mask layer formedby the droplet-discharging method. In other words, the semiconductorlayer 130 is formed so as to cover the source and drain wiring layers122 and 123 (or 124 and 125) (refer to FIG. 36A).

Next, a gate-insulating layer 211 used in the TFT manufactured by theabove process is formed by the plasma CVD method or the sputteringmethod as shown in FIG. 28. It is more preferable that thegate-insulating film 211 is a multilayer including three layers: aninsulating layer formed of silicon nitride; an insulating layer formedof silicon oxide; and an insulating layer 214 formed of silicon nitride.Next, after forming a through hole 223 in the gate-insulating layer 211to expose apart of the source and drain wiring layers 122 and 125, agate electrode layer 279 is formed by the droplet-discharging method(refer to FIG. 28). As the conductive material for forming this layer,it is possible to use the composition mainly including a particle ofmetal such as Ag (silver), Au (gold), Cu (copper), W (tungsten), or Al(aluminum).

A first electrode 233 corresponding to the pixel electrode is formed bydischarging the composition including the conductive material so as toconnect electrically with the source and drain wiring layer 125 throughthe n-type semiconductor layer 129 a. According to the above processes,it is possible to obtain a TFT substrate over which a switching TFT 291,a driver TFT 292, and a capacitor portion 293 are formed (refer to FIG.28).

As shown in FIG. 36B, when the first electrode 233 corresponding to thepixel electrode is formed before forming the gate-insulating layer 211,it is not necessary to expose the source and drain wiring layer 125.

When a bottom-emission type EL display panel is manufactured by adroplet-discharging method, the first electrode 233 may be formed insuch a way that a predetermined pattern is formed using the compositionincluding indium tin oxide (ITO), indium tin oxide including siliconoxide, zinc oxide (ZnO), tin oxide (SnO₂), or the like and then thepattern is annealed.

It is preferable that the first electrode is formed of indium tin oxide(ITO), indium tin oxide including silicon oxide, tin oxide, or the likeby the sputtering method. It is more preferable to use indium tin oxideincluding silicon oxide formed by the sputtering method with the use ofa target in which ITO includes silicon oxide by 2 to 10 wt %.

It is preferable in this embodiment mode that the first electrode 233formed of the indium tin oxide including silicon oxide is formed inclose contact with the insulating layer 214 formed of silicon nitrideincluded in the gate-insulating layer 211. With this structure, it ispossible to obtain an advantage that the proportion of the light emittedto the outside to the light emitted from the EL layer is increased.

Moreover, an insulating layer 248 is formed all over the substrate.After forming the insulating layer 248 by a spin-coating method or a dipmethod, an opening is formed by an etching process as shown in FIG. 28.This process is performed in such a way that the gate-insulating layer211 under the insulating layer 248 at an edge portion of the substrateare etched at the same time so that the first electrode 233 and thesource and drain wiring layer are exposed. When the insulating layer 248is selectively formed by the droplet-discharging method, the etchingprocess is not always necessary. When the droplet-shedding surface isformed over the region where the opening is formed, the opening can beformed in a self-aligning manner.

The insulating layer 248 is formed in such a way that the opening isformed in the position where the light-emitting region is formed inaccordance with the first electrode 233. This insulating layer 248 canbe formed of an inorganic insulating material such as silicon oxide,silicon nitride, silicon oxynitride, aluminum oxide, aluminum nitride,or aluminum oxynitride; acrylic acid, methacryl acid, or a derivative ofthese; heat-resistant polymer such as polyimide, aromatic polyamide, orpolybenzimidazole; or, among the compound made of silicon, oxygen, andhydrogen formed by using a siloxane-based material as a start material,an inorganic siloxane insulating material including a Si—O—Si bond or anorganic siloxane insulating material in which hydrogen over the siliconis substituted by an organic group such as methyl or phenyl. It ispreferable that the insulating layer 248 is formed of a photosensitiveor non-photosensitive material such as acrylic or polyimide because theopening having the cross-sectional shape whose radius of curvaturecontinuously changes is formed so that a thin film in the upper layer isformed without the breakage due to the step.

According to the above processes, a TFT substrate for the EL displaypanel where a top-gate type (also referred to as staggered-type) TFTs291 and 292 and the first electrode 233 are connected over the substrate100 is completed.

Before forming the EL layer 237, the moisture in the insulating layer248 or adsorbed on its surface is removed by means of heat treatment ata temperature of 200° C. under the atmospheric pressure. It ispreferable that after heat treatment at temperatures from 200 to 400°C., preferably from 250 to 350° C. under the reduced pressure, the ELlayer 237 is formed by the vacuum evaporation method or thedroplet-discharging method under the reduced pressure without beingexposed to the atmosphere.

Moreover, a light-emitting element 239 is formed by forming a secondelectrode 238 over the EL layer 237. This light-emitting element 239 isconnected to the driver TFT 292.

Subsequently, a sealing material 240 is formed, and a sealing substrate241 is used for sealing. After that, a flexible wiring substrate 250 maybe connected to the connecting-wiring layer 271. This is the same thingto a signal-wiring layer.

According to the above processes, a light-emitting device having atop-gate type TFT can be manufactured.

Embodiment Mode 8

The method of making a resist mask drop-shedding is explained withreference to FIG. 28 and FIGS. 37A to 40B as the embodiment mode 8.

As shown in FIG. 37A, a photosensitive resin 206, which is a material ofa resist mask, is discharged or applied on a base layer on a substrate100. In the case of applying the photosensitive resin 206, a spin coateror a slit coater may be used. The photosensitive resin 206 may be anegative photosensitive resin or a positive photosensitive resin thatare sensitive to the light in the range of an ultraviolet to infraredregion. The negative photosensitive resin is used in this embodimentmode.

Next, a pattern is written in such a way that the photosensitive resin206 is irradiated with a laser beam 208 using a laser imaging system 207while moving the substrate or the laser.

After developing the photosensitive resin, a resist mask 133 is formedin a region irradiated with the laser beam as shown in FIG. 38A. Sincethe negative photosensitive resin is used here, the region irradiatedwith the laser beam becomes the resist mask.

Next, the resist mask 133 is processed by plasma of fluorine so that theresist mask 133 has a droplet-shedding property.

Next, source and drain wiring layers 135 to 138 are formed by adroplet-discharging method in such a way that a composition including aconductive material is discharged selectively so as to sandwich theresist mask 133 (refer to FIG. 39A). On this occasion, thedroplet-shedding property of the resist mask 133 makes it possible tocontrol a space 230 between the source and the drain wirings preciselyin a self-aligning manner. Subsequently, the base layer 201 isinsulated. On this occasion, the resist mask 133 may be removed or maynot be removed. Then, regions 126 to 129 with phosphous doped, n-typesemiconductor layers 126 a to 129 a, first ekectride 233, agate-insulating film 211 and a semiconductor layer 132 are formedsimilarly as Embodiment Mode 7.

The following processes are the same as those in the embodiment mode 7.

Embodiment Mode 9

A bottom-gate TFT is explained with reference to FIGS. 41A to 46B as theembodiment mode 9.

As shown in FIG. 41A, a gate electrode layer 203 is formed over asubstrate 100 by a plasma CVD method or a sputtering method. The gateelectrode layer 203 may be formed selectively by a droplet-dischargingmethod.

Next, the photosensitive resin 206 is discharged or applied. In the caseof applying the photosensitive resin 206, a spin coater or a slit coatermay be used. The photosensitive resin 206 may be a negativephotosensitive resin or a positive photosensitive resin that aresensitive to the light in the range of an ultraviolet to infraredregion. The negative photosensitive resin is used in this embodimentmode.

Next, a pattern is written in such a way that the photosensitive resin206 is irradiated with a laser beam 208 using a laser imaging system 207while moving the substrate or the laser as shown in FIG. 41B.

After developing, the region irradiated with the laser beam becomes aresist mask 209 as shown in FIG. 42A because the negative photosensitiveresin is used here.

Next, the resist mask 209 is used as a mask to etch the gate electrodelayer 203 by means of a known technique such as dry etching or wetetching, and then the resist mask 209 is removed. As a result, the gateelectrode 203 that is minute can be formed.

Next, a gate-insulating layer 211 is formed in a single-layer ormultilayer structure by the plasma CVD method or the sputtering method(refer to FIG. 43A). It is particularly preferable that thegate-insulating layer is a multilayer including three layers: aninsulating layer formed of silicon nitride, an insulating layer formedof silicon oxide, and an insulating layer formed of silicon nitride.

Next, a solution for forming a droplet-shedding surface is discharged orapplied.

Then, a surface on which the solution for forming the droplet-sheddingsurface applied is washed using ethanol. Thus, an extremely thin filmforming a droplet-shedding surface 224 is formed.

Next, a laser beam of ultraviolet ray or the like is irradiated from therear surface of the substrate for the purpose of exposure. On thisoccasion, since the gate electrode layer 203 blocks the laser beam, theextremely thin film forming the droplet-shedding surface 224 over thegate electrode layer 203 is not exposed. As a result, only the upperpart of the gate electrode layer 203 remains the droplet-sheddingsurface, and the other regions become a droplet-attracting surface(refer to FIG. 43B).

Next, source and drain wiring layers 135 to 138 are formed by adroplet-discharging method in such a way that a composition including aconductive material is discharged selectively (refer to FIG. 44A). Onthis occasion, since the extremely thin film forming thedroplet-shedding surface 224 exists over the gate electrode layer 203, aspace 230 between the source and drain wirings can be minutelycontrolled in a self-aligning manner.

Then, a region 139 with phosphorus doped is formed selectively only oversurfaces of the source and drain wiring layers 135 to 138 by the plasmaimmersion method (refer to FIG. 44B).

On this occasion, an extremely thin film forming droplet-sheddingsurface 224 can be removed by a condition of the plasma doping.

The region with phosphorus doped 139 reacts with a part of asemiconductor layer to be formed afterward so that n-type semiconductorlayers 139 a shown in FIG. 45A are formed.

Next, a semiconductor layer 215 is formed. The semiconductor layer 215is formed of an AS or an SAS manufactured by a vapor growth method or asputtering method with the use of a semiconductor material gas typifiedby silane or germane. As the vapor growth method, the plasma CVD methodor a thermal CVD method can be used.

Next, a resist mask 141 is formed by discharging or applying a negativephotosensitive resin 140, irradiating the negative photosensitive resin140 with a laser beam using a laser imaging system 207 and developingthe photosensitive resin 140. When the resist mask 141 does not need tobe formed minutely, it may be formed by a droplet-discharging apparatus.

Next, the semiconductor layer 215 is patterned by means of etching withthe use of the resist mask 141. After that, a first electrode 233corresponding to a pixel electrode is formed, and then, a protectivefilm 247 is formed.

The following processes are the same as those in the embodiment modes 1and 3.

Embodiment Mode 10

An example of a light-emitting element applicable in the embodimentmodes 1 to 9 is described with reference to FIGS. 19A and 20B.

FIG. 19A is an example in which a first electrode 11 is formed of alight-transmitting conductive oxide material including silicon oxide bythe density of 1 to 15 atomic %. An EL layer 16 in which ahole-injecting or hole-transporting layer 41, a light-emitting layer 42,and an electron-transporting or electron-injecting layer 43 arelaminated is provided over the first electrode 11. A second electrode 17is formed of a first electrode layer 33 including an alkali metal suchas Li or MgAg; or an alkali-earth metal and a second electrode layer 34including a metal material such as aluminum. With this structure, thepixel can emit the light from the side of the first electrode 11 asindicated with an arrow in the figure.

FIG. 19B shows an example in which the light is emitted from the side ofthe second electrode 17. In this figure, the first electrode 11 isformed of a third electrode layer 35 made of a metal such as aluminum ortitanium or a metal material including both the metal and nitrogen bythe concentration of the stoichiometric composition ratio or less andformed of a fourth electrode layer 32 made of a conductive oxidematerial including silicon oxide by the density from 1 to 15 atomic %.An EL layer 16 in which a hole-injecting or hole-transporting layer 41,a light-emitting layer 42, or an electron-transporting orelectron-injecting layer 43 are laminated is provided over the firstelectrode 11. The second electrode 17 is formed of a first electrodelayer 33 including an alkali metal such as LiF or CaF or an alkali-earthmetal and formed of a second electrode layer 34 made of a metal materialsuch as aluminum. When both layers are formed in 100 nm thick or less sothat the light can transmit therethrough, it is possible to emit lightfrom the side of the second electrode 17.

FIG. 20A shows an example to emit light from the first electrode 11 andshows the structure formed by laminating the electron-transporting orelectron-injecting layer 43, the light-emitting layer 42, and thehole-injecting or hole-transporting layer 41 in order. The secondelectrode 17 is formed of the fourth electrode layer 32 made of aconductive oxide material including silicon oxide by the concentrationfrom 1 to 15 atomic % and formed of the third electrode layer 35 made ofa metal such as aluminum or titanium or including both the metal andnitrogen by the concentration of the stoichiometric composition ratio orless. The first electrode 11 is formed of a first electrode layer 33including an alkali metal such as LiF or CaF or an alkali-earth metaland formed of a second electrode layer 34 made of a metal material suchas aluminum. When both layers are formed in 100 nm thick, or less sothat the light can transmit therethrough, it is possible to emit lightfrom the first electrode 11.

FIG. 20B shows an example to emit light from the second electrode 17 andshows the structure formed by laminating the electron-transporting orelectron-injecting layer 43, the light-emitting layer 42, and thehole-injecting or hole-transporting layer 41 in order. The firstelectrode 11 has the same structure as that of FIG. 20A and has the filmthickness of such a degree that the light generated in the EL layer canbe reflected. The second electrode 17 is made of a conductive oxidematerial including silicon oxide by the concentration from 1 to 15atomic %. In this structure, when the hole-injecting orhole-transporting layer 41 is formed of a metal oxide (typicallymolybdenum oxide or vanadium oxide), which is an inorganic material,oxygen that is introduced when forming the fourth electrode 17 issupplied, and the hole-injecting property is enhanced. Accordingly, thedrive voltage can be lowered.

When the first electrode is formed of the light-transmitting conductiveoxide material and when the second electrode is formed so as to transmitthe light therethrough or formed of the light-transmitting conductiveoxide material, the light can be emitted from both the first electrodeand the second electrode.

The EL layer may be formed of a light-emitting material and acharge-injecting-and-transporting material including an organic orinorganic compound. Moreover, the EL layer may include one or pluralkinds selected from the group consisting of a low-molecular organiccompound, a medium-molecular organic compound (an organic compoundhaving molecurality of 20 or less or having a total length of chainedmolecules of 10 □m or less without having sublimation property), and ahigh-molecular organic compound in combination with an inorganiccompound having an electron-injecting property or a hole-injectingproperty.

Among the charge-injecting-and-transporting materials, a material havingparticularly high electron-transporting property is, for example, ametal complex having a quinoline skeleton or a benzoquinoline skeletonsuch as tris (8-quinolinolate) aluminum (abbreviated to Alq3), tris(5-methyl-8-quinolinolate) aluminum (abbreviated to Almq3),bis(10-hydroxybenzo[h]-quinolinolate) beryllium (abbreviated to BeBq2),or bis(2-methyl-8-quinolinolate)-4-phenylphenolate-aluminum (abbreviatedto BAlq). A material having high hole-transporting property is, forexample, aromatic amine based compounds (the compounds having a benzenering-nitrogen bond) such as4,4′-bis[N-(1-naphthyl)-N-phenyl-amino]-biphenyl (abbreviated to □-NPD),4,4′-bis[N-(3-methylphenyl)-N-phenyl-amino]-biphenyl (abbreviated toTPD), 4,4′,4″-tris(N,N-diphenyl-amino)-triphenyl amine (abbreviated toTDATA), or4,4′,4″-tris[N-(3-methylphenyl)-N-phenyl-amino]-triphenylamine(abbreviated to MTDATA).

Moreover, among the charge-injecting-and-transporting materials, amaterial having particularly high electron-injecting property is acompound of alkali metal or alkali-earth metal such as lithium fluoride(LiF), cesium fluoride (CsF), or calcium fluoride (CaF₂). Moreover, amixture of the material having high electron-transporting property suchas Alq3 and the alkali-earth metal such as magnesium (Mg) may be used.

Furthermore, among the charge-injecting-and-transporting materials, amaterial having particularly high hole-injecting property is, forexample, a metal oxide such as molybdenum oxide (MoOx), vanadium oxide(VOx), ruthenium oxide (RuOx), tungsten oxide (WOx), or manganese oxide(MnOx). Moreover, a phthalocyanine compound such as phthalocyanine(abbreviated to H₂Pc) or copper phthalocyanine (CuPC) may be used.

The EL layer may have a structure for displaying full colors by formingEL layers for emitting the light having different wavelengthsrespectively in every pixel. Typically, EL layers corresponding to eachcolor of R (red), G (green), and B (blue) are formed. When a filter fortransmitting the wavelength of the emitted light is provided on the sidewhere the light is emitted from the pixel in this case, the enhancementof the color purity and the prevention of the reflection at the pixelcan be expected. The filter (coloring layer) can replace a circularpolarizer, which has been required conventionally, and can suppress theloss of the light emitted from the EL layer. Moreover, the change of thecolor tone in the pixel portion (display screen) when observed obliquelycan be suppressed.

Various materials can be used as the light-emitting material. Amonglow-molecular organic light-emitting materials, it is possible to use4-(dicyanomethylene)-2-methyl-6-(1,1,7,7-tetramethyljulolidin-9-enyl)-4H-pyran(abbreviated to DCJT);4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidin-9-enyl)-4H-pyran(abbreviated to DPA); periflanthene;2,5-dicyano-1,4-bis(10-methoxy-1,1,7,7-tetramethyljulolidin-9-enyl)benzene;N,N′-dimethylquinacridone (DMQd); coumarin 6; coumarin 545T; tris(8-quinolinolato) aluminum; 9,9′-bianthryl; 9,10-diphenylanthracene(abbreviated to DPA); 9,10-bis (2-naphthyl) anthracene (abbreviated toDNA); or the like. Another material can be also used.

On the other hand, since a high-molecular organic light-emittingmaterial has higher physical strength than the low-molecular organiclight-emitting material, a light-emitting element manufactured using theformer material has higher resistance than that manufactured using thelatter material. In addition, since the high-molecular organiclight-emitting material can be formed by a coating method, thelight-emitting element can be manufactured comparatively easily. Astructure of the light-emitting element manufactured using thehigh-molecular organic light-emitting material is basically the same asthat manufactured using the low-molecular organic light-emittingmaterial. Specifically, the light-emitting element has the structure ofcathode/organic EL layer/anode. However, when the EL layer is formedusing the high-molecular organic light-emitting material, it isdifficult to form the same multilayer as that obtained when the EL layeris formed using the low-molecular organic light-emitting material. Inmany cases, it is difficult that the EL layer formed using thehigh-molecular organic light-emitting material has the same multilayerstructure as that when the EL layer is formed using the low-molecularorganic light-emitting material. Specifically, when the high-molecularorganic light-emitting element is used, the structure is cathode/ELlayer/hole-transporting layer/anode.

The color of the emitted light is determined by the material of the ELlayer. When the material of the EL layer is selected appropriately, thelight-emitting element for emitting the light having the desired colorcan be formed. As a high-molecular electroluminescent material,polyparaphenylenevinylene, polyparaphenylene, polythiophene,polyfluorene, or the like is given.

As the polyparaphenylenevinylene material, there are a derivative ofpoly (paraphenylenevinylene) [PVP]; poly(2,5-dialkoxy-1,4-phenylenevinylene) [RO-PPV]; poly(2-(2′-ethyl-hexoxy)-5-methoxy-1,4-phenylenevinylene) [MEH-PPV]; poly(2-(dialkoxyphenyl)-1,4-phenylenevinylene) [ROPh-PPV], and the like. Asthe polyparaphenylene material, there are a derivative ofpolyparaphenylene [PPP]; poly (2,5-dialkoxy-1,4-phenylene) [RO-PPP];poly (2,5-dihexoxy-1,4-phenylene); and the like. As the polythiophenematerials, there are a derivative of polythiophene [PT]; poly(3-alkylthiophene) [PAT]; poly (3-hexylthiophene) [PHT]; poly(3-cyclohexylthiophene) [PCHT]; poly (3-cyclohexyl-4-methylthiophene)[PCHMT]; poly [3-(4-octylphenyl)-thiophene] [POPT]; poly[3-(4-octylphenyl)-2,2′ bithiophene] [PTOPT]; and the like. As thepolyfluorene material, there are a derivative of polyfluorene [PF],poly(9,9-dialkylfluorene) [PDAF]; poly(9,9-dioctylfluorene) [PDOF]; andthe like.

When a high-molecular organic light-emitting material having ahole-transporting property is formed between the anode and ahigh-molecular organic light-emitting material having a light-emittingproperty, it is possible to enhance the hole-injecting property from theanode. Generally, an aqueous solution in which the high-molecularorganic light-emitting material having the hole-transporting property isdissolved together with an acceptor material is applied by a spincoating method or the like. Since the high-molecular organiclight-emitting material having the hole-transporting property isinsoluble in an organic solvent, it can form a multilayer with theorganic light-emitting layer having the light-emitting property. As thehigh-molecular organic light-emitting material having thehole-transporting property, there are a mixture of PEDOT and camphoricsulfonic acid (CSA) as the acceptor material; a mixture of polyaniline[PANI] with polystyrene sulfonic acid [PSS] as the acceptor material;and the like.

The EL layer may have the structure for emitting a single color or awhite color. In the case of using a material for emitting the whitecolor, a filter (color layer) for transmitting a specified wavelengthmay be provided in the side of the pixel to which the light is emittedin order to achieve the color display.

The EL layer for emitting the white color can be obtained by forming,for example, Alq3, Alq3 with nile red, which is a pigment for emittingthe red light, doped partially, Alq3, p-EtTAZ, and TPD (aromaticdiamine) in order by an evaporation method. When the EL layer is formedby the coating method using a spin coater, it is preferable to annealthe EL layer by heating in vacuum after applying the EL layer. Forexample, the EL can be formed in such a way that poly(ethylenedioxythiophene)/poly (stylene sulfonic acid) aqueous-solution(PEDOT/PSS) is applied all over the substrate and annealed, and then apolyvinylcarbazole (PVK) doped with pigment that contributes to thelight emission and serves as the EL layer is applied and bakedthereafter. Such pigment is, for example1,1,4,4-tetraphenyl-1,3-butadiene (TPB);4-dicyanomethylene-2-methyl-6-(p-dimethylamino-styryl)-4H-pyran (DCM1);nile red; coumarine 6; or the like.

The EL layer may be a single layer. For example, 1,3,4-oxadiazolederivative (PBD) having an electron-transporting property may bediffused in the polyvinylcarbazole (PVK) having the hole-transportingproperty. When the PBD is diffused by 30 wt % as the electrontransporter and four kinds of pigments (TPB, coumarin 6, DCM1, and nilered) are diffused by an appropriate amount, white-color emission can beobtained. Not only the light-emitting element for emitting the whitecolor shown in the above but also another light-emitting element foremitting red, green, or blue light can be obtained by selecting thematerial of the EL layer appropriately.

Moreover, the EL layer may be formed of not only a singlet-excitedlight-emitting material but also a triplet-excited material including ametal complex or the like. For example, among pixels for emitting red,green, and blue light, the pixel for emitting the red color, which has arelatively short half-life period of luminance, is formed of thetriplet-excited light-emitting material and the other two pixels areformed of the singlet-excited light-emitting material. Thetriplet-excited light-emitting material has an advantage of low powerconsumption to obtain the same luminance as that of the singlet-excitedlight-emitting material because the triplet-excited light-emittingmaterial has higher light-emission efficiency. In other words, when thepixel for the red color is formed of the triplet-excited light-emittingmaterial, the reliability can be improved because the light-emittingelement requires smaller amount of current. For lower power consumption,the pixels for the red and green colors may be formed of thetriplet-excited light-emitting material and the pixel for the blue colormay be formed of the singlet-excited light-emitting material. When thelight-emitting element of the green color that is highly visible to thehuman eyes is formed of the triplet-excited light-emitting material, thepower consumption can be further reduced.

As an example of the triplet-excited light-emitting material, there is amaterial with a metal complex doped: a metal complex mainly includingplatinum, which is a third transition series element; a metal complexmainly including iridium or the like. Not only the above metal complexbut also another compound that has the above structure and mainlyincludes an element belonging to 8th to 10th group in the periodic tablecan be used as the triplet-excited light-emitting material.

The above-mentioned materials for forming the EL layer are justexamples, and the light-emitting element can be formed by formingfunctional layers such as hole-injecting-and-transporting layer, ahole-transporting layer, an electron-injecting-and-transporting layer, alight emitting layer, an electron-blocking layer, a hole-blocking layer,and the like. Moreover, a mixed layer or a mixed junction in which theselayers are mixed may be formed. It is noted that the EL layer may haveany structure within the scope of the present invention. For example,instead of the particular electron-injecting region and thelight-emitting region, an electrode may be provided, or thelight-emitting material may be diffused in the EL layer for the samepurpose as those regions.

The light-emitting element formed of the above material emits light bybiasing in a forward direction. A pixel of a display device formed usingthe light-emitting element is driven by a simple matrix method or anactive matrix method shown in the embodiment 2. In any way, therespective pixels emit light by biasing in the forward direction in aparticular timing and their emission stops for a certain period. Thereliability of the light-emitting element can be enhanced by biasing ina reverse direction this non-emission period. The light-emitting elementhas a deterioration mode in which the luminance intensity decreasesunder a constant drive condition and another deterioration mode in whichthe luminance appears to be lowered because the non-emission regionexpands. However, when the light-emitting element is driven by biasingin the forward and reverse directions alternately, the speed ofdeterioration can be decelerated, and the reliability of thelight-emitting device can be improved.

Embodiment Mode 11

With reference to FIGS. 21A to 22B, this embodiment mode explains anexample in which a driver circuit is mounted over a display panelmanufactured according to any one of the embodiment modes 1 to 6.

First, a display device employing a COG method is explained withreference to FIGS. 21A and 21B. A pixel portion 1002 for displaying apiece of information with a letter or an image and scanning line drivercircuits 1003 and 1004 are provided over a substrate 1001. Substrates1005 and 1008 with a plurality of driver circuits provided thereover aredivided into rectangles, and the divided driver circuits (hereinaftereach of them is referred to as a driver IC) are mounted over thesubstrate 1001. FIG. 21A shows an example in which a plurality of tapes1006 are mounted to a plurality of driver ICs 1007 respectively. FIG.21B shows an example in which a plurality of tapes 1009 are mounted to adriver IC 1010.

Next, a display device employing a TAB method is explained withreference to FIGS. 22A and 22B. The pixel portion 1002 and the scanningline driver circuits 1003 and 1004 are provided over the substrate 1001.FIG. 22A shows an example in which a plurality of tapes 1006 are pastedover the substrate 1001 and then driver ICs 1007 are mounted over theplurality of tapes 1006 respectively. On the other hand, FIG. 22B showsan example in which a tape 1009 is pasted over a substrate 1001 and thena driver IC 1010 is mounted over the tape 1009. In the case of employingthe latter one, a metal chip for fixing the driver IC 1010 may be pastedtogether in consideration of the strength.

In order to improve the productivity, a plurality of driver ICs mountedover these display panels may be manufactured over the rectangularsubstrates 1005 and 1008 having a side of 300 mm or more.

In other words, a plurality of circuit patterns including both a drivercircuit portion and an input/output terminal as a unit may be formedover the substrates 1005 and 1008, and then the substrates 1005 and 1008may be divided. The driver IC may be a rectangle having a long side from15 to 80 mm and a short side from 1 to 6 mm as shown in FIGS. 21A and22A in consideration of the length of one side of the pixel portion andthe pixel pitch. Moreover, the driver IC may have the length of one sideof the pixel portion 1002 or the total length of one side of the pixelportion 1002 and one sides of the respective driver circuits 1003 and1004 as shown in FIGS. 21B and 22B.

The primacy of an outer size of the driver IC to the IC chip lies in thelength of the long side. When the driver IC having a long side from 15to 80 mm is used, the number of driver ICs required to be mounted to thepixel portion 1002 is fewer than that of IC chips, thereby boosting theproduction yield. Moreover, when the driver IC is formed over the glasssubstrate, the shape of the substrate to be used as a base material isnot limited, and therefore the productivity is not affected adversely.This is very advantageous in comparison with the case where the IC chipis taken out from a circular silicon wafer.

In FIGS. 21A to 22B, the driver IC 1007 or 1009 with the driver circuitformed is mounted outside the pixel portion 1002 over the substrate.These driver ICs 1007 and 1010 are signal line driver circuits. In orderto form the pixel region corresponding to the full color of R, G, and B,the signal lines as many as 3072 lines are necessary for XGA class andthe signal lines as many as 4800 lines are necessary for UXGA class.Such a number of signal lines form lead wirings by being divided intoseveral blocks at the end of the pixel portion 1002, and the dividedsignal lines are collected in accordance with the pitch of outputterminals of the driver ICs 1007 and 1010.

It is preferable that the driver IC 1007 and 1010 are each formed usinga crystalline semiconductor over the substrate, and it is alsopreferable that the crystalline semiconductor is formed by beingirradiated with continuous wave laser light. Therefore, a continuouswave solid-state laser or gas laser is used as an oscillator forgenerating the laser light. With the continuous wave laser light, it ispossible to manufacture a transistor formed of a poly-crystallinesemiconductor layer having a large crystal grain size and few crystaldefects. Moreover, since the poly-crystalline semiconductor film issuperior in the mobility and the speed of response, high-speed operationis possible, and operation frequency of the semiconductor element formedof the poly-crystalline semiconductor can be improved compared to thatof the conventional semiconductor element. Moreover, since the variationof the characteristic is reduced, high reliability can be obtained. Itis noted that a channel-length direction of the transistor may conformto the scanning direction of the laser beam for the purpose of improvingthe operation frequency further. This is because, in the lasercrystallization step by the continuous wave laser light, the highestmobility can be obtained when the channel-length direction of thetransistor and the scanning direction of the laser beam areapproximately parallel (preferably the angle between the two directionsis in the range of −30° to 30°. It is noted that the channel-lengthdirection conforms to the direction in which the current flows, whichmeans the direction in which the charge moves, in the channel-formingregion. The transistor manufactured thus has an active layer formed of apoly-crystalline semiconductor layer in which the crystal grain extendsin the channel direction. This means that the crystal grain boundarybasically extends in the channel direction.

To perform the laser crystallization, it is preferable to form the beamspot of the laser beam so that the width of the beam spot ranges fromapproximately 1 to 3 mm, which is the same length as the short side ofthe driver IC. Moreover, it is preferable that the beam spot has a verythin line shape in order to secure enough and efficient energy densityto the irradiated object. However, the term of linear herein used doesnot mean a line in a strict sense but means a rectangle or an oblonghaving a large aspect ratio, for example 2 or more (preferably 10 to10000). Thus, a method for manufacturing a display device in which theproductivity is improved can be provided by making the width of the beamspot of the laser light the same as the length of the short side of thedriver IC.

FIGS. 21A to 22B show the examples in which the scanning line drivercircuit is formed integrally with the pixel portion and the driver IC ismounted as the signal line driver circuit. However, the presentinvention is not limited to this, and the driver IC may be mounted asboth of the scanning line driver circuit and the signal line drivercircuit. In this case, the specification of the driver IC may be madedifferent on the scanning line side and on the signal line side.

In the pixel portion 1002, the signal lines and the scanning linesintersect to form a matrix, and the transistors are arranged at therespective intersections. In the present invention, TFTs each of whichuses an amorphous semiconductor or a semi-amorphous semiconductor as achannel portion are arranged in the pixel portion 1002. The amorphoussemiconductor is formed by the plasma CVD method, the sputtering method,or the like. The semi-amorphous semiconductor can be formed at atemperature of 300° C. or less by the plasma CVD method and has anadvantage that it can be formed in short time in the thickness requiredto form the transistor even when, for example, a non-alkali glasssubstrate having an outer size as large as 550×650 mm is used. Theadvantage of such a manufacturing technique is effective inmanufacturing a large-sized display device. Moreover, a semi-amorphousTFT can obtain the electric field mobility from 2 to 10 cm²/V·sec whenthe channel-forming region thereof is formed of the SAS. Therefore, thisTFT can be used as a switching element of the pixel or the semiconductorelement constituting the scanning line driver circuit. Accordingly, adisplay panel achieving the system-on-panel can be manufactured.

It is noted that, in FIGS. 21A to 22B, the scanning line driver circuitis also formed integrally over the substrate by using the TFT in whichthe semiconductor layer is formed of the SAS according to the embodimentmode 6. In the case of using the TFT in which the semiconductor layer isformed of the AS, the driver ICs may be mounted as both of the scanningline driver circuit and the signal line driver circuit.

In this case, it is preferable to differ the specification of the driverICs used on the scanning line side and the signal line side. Forexample, while the transistor constituting the driver IC on the scanningline side requires the withstanding voltage of approximately 30 V, thedriving frequency thereof is 100 kHz or less, and the high-speedoperation is not required that much. Therefore, it is preferable to setthe channel length (L) of the transistor constituting the driver on thescanning line side to be sufficiently long. On the other hand, thewithstanding voltage of approximately 12 V is enough in the transistorconstituting the driver IC on the signal line side, while the drivingfrequency is approximately 65 MHz at 3 V, and the high-speed operationis required. For this reason, it is preferable to set the channel lengthof the transistor constituting the driver and the like on the order ofmicrometer.

Thus, the driver circuit can be built in the display panel.

Embodiment Mode 12

With reference to FIGS. 60A and 60B, this embodiment mode explains anexample in which a driver circuit is mounted over the display panelmanufactured by any one of the embodiment modes 3 to 5.

FIGS. 60A and 60B show a structure in which the driver IC is mountedover a display panel shown in FIG. 2 by a COG (Chip On Glass). FIG. 60Ashows a structure in which a driver IC 3106 is mounted over a TFTsubstrate 3200 by using an anisotropic conductive material as anadhesive agent. A pixel portion 3101 and a signal line input terminal3104 (the same applies to a scanning line input terminal) are formedover the TFT substrate 3200. An opposing substrate 4229 is adhered tothe TFT substrate 3200 by a sealing material 4226, and a liquid crystallayer 4230 is formed between the opposing substrate 4229 and the TFTsubstrate 3200.

An FPC 3812 is adhered to the signal line input terminal 3104 by ananisotropic conductive material. The anisotropic conductive materialincludes a resin 3815 and a conductive particle 3814 having a diameterfrom several tens to several hundred □m with its surface plated by Au orthe like. The conductive particle 3814 connects electrically the signalline input terminal 3104 and a wiring 3813 formed at the FPC 3812. Thedriver IC 3106 is adhered to the TFT substrate 3200 by the anisotropicconductive material, and a conductive particle 3810 mixed in the resin3811 connects electrically an input/output terminal 3809 provided at thedriver IC 3106 and the signal line input terminal 3104.

Moreover, as shown in FIG. 60B, the driver IC 3106 is adhered to the TFTsubstrate 3200 by an adhesive material 3816, and an input/outputterminal of the driver IC may be connected with the lead wiring or theconnection wiring by an Au wire 3817. Then, a sealing resin 3818 is usedto seal them. It is noted that the method for mounting the driver IC isnot limited in particular, and a known method such as the COG method, awire bonding method, or a TAB method can be used.

When the thickness of the driver IC is the same as that of the opposingsubstrate, both of them have almost the same height, and therefore thedisplay device can be thinned as a whole. Moreover, when the respectivesubstrates are manufactured using the same material, thermal stress isnot generated even when the temperature of the display device changes,and the characteristic of the circuit manufactured by the TFT does notdeteriorate. Moreover, as shown in this embodiment mode, when the drivercircuit is mounted by the driver IC whose length is longer than that ofthe IC chip, the number of driver ICs to be mounted to one pixel regioncan be decreased.

As thus described, the driver circuit can be built in the display panel.

Embodiment Mode 13

A structure of a pixel of a display panel shown in this embodiment modeis explained with reference to equivalent circuit diagrams of FIGS. 23Ato 23F.

In a pixel shown in FIG. 23A, a signal line 410 and power supply lines411 to 413 extend in a column direction and a scanning line 414 extendsin a row direction. Moreover, the pixel shown in FIG. 23A includes aswitching TFT 401, a driver TFT 403, a current control TFT 404, acapacitor element 402, and a light-emitting element 405.

A pixel shown in FIG. 23C has the same structure as the pixel shown inFIG. 23A except that a gate electrode of the driver TFT 403 is connectedto a power supply line 413 extending in the row direction. In otherwords, both pixels in FIGS. 23A and 23C have the same equivalent circuitdiagram. However, the power supply lines are formed of differentconductive layers in the case where the power supply line 413 extends inthe column direction (FIG. 23A) and in the case where the power supplyline 413 extends in the row direction (FIG. 23C). Here, attention ispaid to the wirings connected to the gate electrode of the driver TFT403, and the pixel is drawn separately as shown in FIGS. 23A and 23C inorder to show that the layer for manufacturing these wirings isdifferent.

The characteristic of the pixel shown in FIGS. 23A and 23C is that thedriver TFT 403 is connected serially with the current control TFT 404 inthe pixel and that L3/W3:L4/W4=5 to 6000:1 where L3 is the channellength of the driver TFT 403, W3 is the channel width of the driver TFT403, L4 is the channel length of the current control TFT 404, and W4 isthe channel width of the current control TFT 404. As an example ofsatisfying this equation, L3 is 500 μm, W3 is 3 μm, L4 is 3 μm, and W4is 100 μm.

The driver TFT 403 operates in a saturation region and controls thecurrent value flowing to the light-emitting element 405, and the currentcontrol TFT 404 operates in a linear region and controls whether or notthe current is supplied to the light-emitting element 405. It ispreferable that both TFTs have the same conductivity type in themanufacturing process. Moreover, not only an enhancement type but also adepletion type may be employed as the driver TFT 403. Since the currentcontrol TFT 404 operates in the linear region in the present inventionhaving the above structure, the slight fluctuation of the VGS of thecurrent control TFT 404 does not affect the current value of thelight-emitting element 405. That is to say, the current value of thelight-emitting element 405 is determined by the driver TFT 403 operatingin the saturation region. The present invention having the abovestructure can provide a display device in which the image quality isenhanced by suppressing the variation of the luminance of thelight-emitting element due to the variation of the characteristic of theTFT.

In the pixels shown in FIGS. 23A to 23D, the switching TFT 401 controlsthe input of the video signal into the pixel. When the switching TFT 401is turned on to input the video signal into the pixel, the video signalis held by the capacitor element 402. Although FIGS. 23A and 23C showthe structure providing the capacitor element 402, the present inventionis not limited to this, and the capacitor element 402 may not beprovided in the case where a gate capacitor can work as the capacitorfor holding the video signal.

The light-emitting element 405 has a structure in which anelectroluminescent layer is sandwiched between two electrodes, and apotential difference is provided between the pixel electrode and theopposing electrode (between the anode and the cathode) so that thevoltage is applied in the direction of forward bias. Theelectroluminescent layer can be formed of various kinds of materialssuch as an organic material or an inorganic material. The luminescencefrom this electroluminescent layer includes a luminescence(fluorescence) emitted when returning from a singlet-excited state to aground state and a luminescence (phosphorescence) emitted when returningfrom a triplet-excited state to the ground state.

The pixel shown in FIG. 23B has the same structure as that shown in FIG.23A except that a TFT 406 and a scanning line 415 are added. In the sameway, the pixel shown in FIG. 23D has the same structure as that shown inFIG. 23C except that the TFT 406 and a scanning line 415 are added.

Turning on and off the TFT 406 is controlled by the scanning line 415newly provided. When the TFT 406 is turned on, the charge held in thecapacitor element 402 is discharged, and the control TFT 404 is turnedoff. That is to say, the TFT 406 can form a condition compellingly notfor flowing the current to the light-emitting element 405. Therefore,the structures of FIGS. 23S and 23D can increase the duty ratio becausethe lighting period can start at the same time as or just after thestart of the writing period without waiting the writing of the signal toall the pixels.

In a pixel shown in FIG. 23E, a signal line 450 and power supply lines451 and 452 extend in the column direction, and a scanning line 453extends in the row direction. Moreover, the pixel shown in FIG. 23Eincludes a switching TFT 441, a driver TFT 443, a capacitor element 442,and a light-emitting element 444. A pixel shown in FIG. 23F has the samepixel structure as that shown in FIG. 23E except that a TFT 445 and ascanning line 454 are added. The structure of FIG. 23F can also increasethe duty ratio by providing the TFT 445.

Embodiment Mode 14

With reference to FIG. 17, this embodiment mode explains an example inwhich protective diodes are provided to a scanning line input terminalportion and a signal line input terminal portion respectively. TFTs 501and 502 are provided in a pixel in FIGS. 17 and 18. This TFT has thesame structure as that explained in the embodiment mode 1.

Protective diodes 561 and 562 are provided in the signal line inputterminal portion. These protective diodes are manufactured in the sameprocess for forming the TFTs 501 and 502, and they can work as thediodes by connecting the gate and one of the drain and the source. FIG.18 is an equivalent circuit diagram of the top view shown in FIG. 17.

The protective diode 561 is formed of a gate electrode layer 550, asemiconductor layer 551, an insulating layer 552 for protecting achannel, and a wiring layer 553. The protective diode 562 has the samestructure. Common potential lines 554 and 555 to connect with theseprotective diodes 561 and 562 are formed of the same layer as the gateelectrode layer. Therefore, it is necessary to form a contact hole inthe gate-insulating layer in order to connect with the wiring layer 553electrically.

The contact hole can be formed in the gate-insulating layer in such away that a mask layer is formed by a droplet-discharging method and thenetching is performed using the mask layer. In this case, when theetching is performed by the atmospheric-pressure discharging, localelectric discharging is possible, and it is not necessary to form themask layer all over the substrate.

The signal-wiring layer 250 is formed of the same layer as the sourceand drain wiring layer 225 in the TFT 501, and the signal-wiring layer250 and wiring layer 225 is connected.

The scanning line input terminal portion has the same structure. Thus,the protective diodes provided at an input stage can be formedsimultaneously according to the present invention. It is noted that theposition where the protective diode is inserted is not limited to thatshown in this embodiment mode, and the protective diode may be providedbetween the driver circuit and the pixel.

Embodiment Mode 15

FIGS. 29 and 30 show an example in which an EL display module is formedusing a TFT substrate 200 manufactured by a droplet-discharging method.In both figures, a pixel portion 101 including pixels 102 a to 102 c isformed over the TFT substrate 200.

In FIG. 29, a TFT having the same structure as that of a TFT formed inthe pixel or a diode formed by connecting a gate of the TFT with one ofa source and a drain thereof is provided as a protective circuit portion701 between a driver circuit 703 and pixels 102 a to 102 c outside thepixel portion 101. As the driver circuit 703, a driver IC feinted of asingle crystal semiconductor, a stick driver IC formed of apoly-crystalline semiconductor film over a glass substrate, a drivercircuit formed of an SAS, or the like is applied.

The TFT substrate 200 shown by FIG. 29 is adhered to a sealing substrate241 through a spacer 710 formed over an insulating layer 248 by adroplet-discharging method. The spacer 710 is preferably provided inorder to keep the same gap between the two substrates even when thesubstrate is thin and the size of the pixel portion is large. The space702 between the TFT substrate 200 and the sealing substrate 241 over thelight-emitting element may be filled with a light-transmitting resinmaterial, which may be solidified thereafter. Alternatively, theairspace may be filled with anhydrous nitrogen or inert gas.

FIG. 29 shows the case in which the light-emitting element 239 is atop-emission type that emits light in a direction indicated by arrows.The image can be displayed with many colors by differing the colorsemitted from the respective pixels 102 a to 102 c so as to be red,green, or blue. Moreover, color purity of the light emitted to theoutside can be enhanced by forming coloring layers corresponding to therespective colors on the side of the sealing substrate 241. Furthermore,the pixels 102 a, 102 b, and 102 c may be white light-emitting elementsand they may be combined with the coloring layers.

An external circuit 705 in FIGS. 29 and 30 is connected to a scanningline or signal line connection terminal provided at one end of the TFTsubstrate 200 by a wiring substrate 704. Moreover, a heat pipe 706 and aradiator plate 707 may be provided in contact with or adjacent to theTFT substrate 200 to increase the heat-releasing effect as shown in FIG.29.

Although FIG. 29 shows the top-emission type EL module, abottom-emission structure as shown in FIG. 30 may be also employed bychanging the structure of the light-emitting element or the position ofthe external circuit substrate.

FIG. 30 shows an example for forming a sealing structure by filling thespace 702 with an adhesive resin 702 and pasting a resin film 708 usingthe sealing material 240 and the adhesive resin 702 over the TFTsubstrate 200 where the pixel portion is formed. It is preferable toprovide a gas barrier film for preventing the transmission of themoisture over the surface of the resin film 708. Although FIG. 30 showsthe bottom-emission structure in which the light generated in thelight-emitting element is emitted through the substrate, a top-emissionstructure can be also obtained by making the resin film 708 and theadhesive resin 702 have a light-transmitting property. In any way,further thinning and light-weighting can be achieved by employing thefilm-sealing structure.

Embodiment Mode 16

A television receiver can be completed by the display modulemanufactured by the embodiment mode 15 or the display panel manufacturedby the embodiment mode 11 or 12. FIG. 31 is a block diagram showing amain structure of the television receiver. The display panel may haveany structure. One example is that, as shown in FIG. 1, only a pixelportion 101 is formed over a substrate, and a scanning line drivercircuit 903 and a signal line driver circuit 902 are mounted over thesubstrate by a TAB method. Another example is that, as shown in FIG. 2,the pixel portion 101 and the scanning line driver circuit 903 and thesignal line driver circuit 902 around the pixel portion 101 are mountedby a COG method. Another example is that, as shown in FIG. 3, a TFT isformed of an SAS, the pixel portion 101 and the scanning line drivercircuit 903 are formed integrally over the substrate, and the signalline driver circuit 902 is mounted as a driver IC. Any structure may beemployed as the display panel.

On the side to which the video signal is input, a video signal amplifiercircuit 905 for amplifying a video signal among signals received by atuner 904; a video signal process circuit 906 for converting the signaloutput from the vide signal amplifier circuit 905 into a color signalcorresponding to each color of red, green, and blue; a control circuit907 for converting the video signal into an input specification of thedriver IC; and the like are provided. The control circuit 907 outputssignals to the sides of the scanning line and the signal linerespectively. In the case of digital driving, a signal splitter circuit908 may be provided on the side of the signal line so that an inputdigital signal is split into m number of signals and supplied.

Among the signals received by the tuner 904, an audio signal is sent toan audio signal amplifier circuit 909 and supplied to a speaker 913through an audio signal process circuit 910. A control circuit 911receives pieces of control information about a received station(received frequency) and the volume from the input portion 912, and thensends a signal to the tuner 904 and the audio signal process circuit910.

When these external circuits and the EL module explained in FIGS. 29 and30 are built in a chassis 920, a television receiver can be completed. Adisplay screen 921 is formed by the EL display module, and a speaker922, an operation switch 924, and the like are provided as accessories.Thus, the television receiver can be completed by the present invention.

Of course, the present invention is not limited to the televisionreceiver, and the present invention can be applied to a monitor of apersonal computer and to a display medium, particularly a large one,such as a information display panel at a railway station or an airport,an advertisement display panel at a street, and the like.

Embodiment Mode 17

A top-gate TFT is explained as the embodiment mode 17 with reference toFIGS. 64 and 36B.

The structure shown in FIG. 36A is formed similarly as Embodiment Mode7.

Next, a gate-insulating layer 211 is formed over the semiconductor layer130 and the pixel electrode 142 as shown in FIG. 36B. Then, asemiconductor layer 132 is formed over the gate-insulating layer 211 tomanufacture a TFT.

FIG. 64 is a cross-sectional view of a liquid crystal display panelmanufactured by this embodiment mode. In FIG. 64, unlike FIG. 36B, thegate-insulating layer is formed before forming the semiconductor layerand the pixel electrode. Here, a gate-insulating layer 211 is formed bythe plasma CVD method or the sputtering method. It is particularlypreferable that the gate-insulating layer 211 is a multilayer includingthree layers: an insulating layer formed of silicon nitride; aninsulating layer formed of silicon oxide; and an insulating layer formedof silicon nitride. Next, after forming a through hole in thegate-insulating layer 211 to expose a part of the source and drainwiring layer 125, a pixel electrode layer 233 is formed by discharging acomposition including a conductive material selectively so as to connectelectrically with the source and drain wiring layer 125 through ann-type semiconductor layer. When the pixel electrode layer 233 is formedbefore forming the gate-insulating layer 131 as shown in FIG. 36B, it isnot necessary to expose the source and drain wiring.

A gate electrode layer 3279 is formed by a droplet-discharging method.As the conductive material for forming this layer, it is possible to usethe composition mainly including a particle of Ag (silver), Au (gold),Cu (copper), W (tungsten), Al (aluminum), or the like.

After a sealing material 3231 is formed, a substrate 3100 is pasted withthe sealing material 3231 to an opposing substrate 3234 over which aconductive layer 3233 functioning as an opposing electrode and aninsulating layer 3232 functioning as an orientation film are formed.After that, a liquid crystal layer 3350 is formed between the substrate3100 and the opposing substrate 3234. Next, a region to which aconnection terminal 3236 is pasted is exposed by means of etching underthe atmospheric pressure or the near-atmospheric pressure, and theconnection terminal is pasted to this region. Thus, a liquid crystaldisplay panel having a display function can be manufactured (refer toFIG. 64).

Embodiment Mode 18

This embodiment mode explains an example in which protective diodes areprovided to a scanning line input terminal portion and a signal lineinput terminal portion respectively with reference to FIG. 62. A TFT3260 is provided in a pixel 3102 in FIG. 62. This TFT has the samestructure as that explained in the embodiment mode 3.

Protective diodes 3261 and 3262 are provided in the signal line inputterminal portion. These protective diodes are manufactured in the sameprocess for forming the TFT 3260, and they work as the diodes byconnecting the gate with one of the drain and the source. FIG. 63 is anequivalent circuit diagram of the top view shown in FIG. 62.

The protective diode 3261 includes a gate electrode layer 3250, asemiconductor layer 3251, an insulating layer 3252 for protecting achannel, and a wiring layer 3253. The protective diode 3262 has the samestructure. Common potential lines 3254 and 3255 to connect with theseprotective diodes 3261 and 3262 are formed of the same layer as the gateelectrode layer 3250. Therefore, it is necessary to form a contact holein the gate-insulating layer in order to connect with the wiring layer3253 electrically.

The contact hole can be formed in the gate-insulating layer in such away that a mask layer is formed by a droplet-discharging method and thenetching is performed using the mask layer. In this case, when theetching is performed by the atmospheric-pressure discharging, localelectric discharging is possible, and it is not necessary to form themask layer all over the substrate.

The protective diodes 3261 and 3262 are formed of the same layer as thesource and drain wiring layers 3225 and 3226 in the TFT 3226, and thesignal-wiring layer 3256 connected thereto is connected to the side of asource or drain of the protective diodes 3261 and 3262.

The scanning line input terminal portion has the same structure. Thus,the protective diodes 3261 and 3262 provided at the input line can beformed simultaneously according to the present invention. It is notedthat the positions where the protective diodes 3261 and 3262 areinserted are not limited to those shown in this embodiment mode, andthey may be provided between the driver circuit and the pixel.

Embodiment Mode 19

A television receiver can be completed using the display panelmanufactured according to the embodiment mode 12. FIG. 31 is a blockdiagram for showing the main structure of the television receiver. Themain structure of the television receiver is the same as that shown inthe embodiment mode 16.

FIG. 61 shows an example of a display module in which a TFT substrate4200 and an opposing substrate 4229 are adhered by a sealing material4231, and a display region provided with a pixel portion 4101 and aliquid crystal layer 4230 is formed between the TFT substrate 4200 andthe opposing substrate 4229. A coloring layer 4250 is necessary in thecase of a color display, and the coloring layers corresponding to therespective colors of red, green, and blue are provided to the respectivepixels. Polarizing plates 4251 and 4252 are provided outside the TFTsubstrate 4200 and the opposing substrate 4229. A protective layer 4280is formed over the polarizing plate 4251. A light source includes acold-cathode tube 4258 and an optical waveguide 4259. A circuitsubstrate 4257 is connected to the TFT substrate 4200 by a flexiblewiring substrate 4256, and an external circuit such as a control circuitor a power supply circuit is built-in.

FIG. 32 shows the television receiver completed by building this displaymodule in a chassis 920. A display screen 921 is foamed by the displaymodule, and a speaker 922, an operation switch 924, and the like areprovided as accessories. Thus, a television receiver can be completed bythe present invention.

The present invention is not limited to the television receiver, and itcan be applied to a monitor of a personal computer and a display medium,particularly a large one, such as an information display panel at arailway station or an airport or an advertisement display panel at astreet.

1. A method for manufacturing a display device comprising: forming abase layer comprising a metal material over a substrate; forming a gateelectrode over a first portion of the base layer; insulating a secondportion of the base layer; forming a gate insulating film over the gateelectrode and the second portion of the base layer, the gate insulatingfilm comprising a plurality of insulating layers; forming a firstsemiconductor layer over the gate insulating film, the firstsemiconductor layer comprising a microcrystalline semiconductor; forminga second semiconductor layer over the first semiconductor layer; etchingthe first semiconductor layer and the second semiconductor layer,thereby forming a semiconductor island and an impurity region; formingsource and drain wiring layers over the impurity region; and etching theimpurity region using the source and drain wiring layers as masks,thereby forming source and drain regions, wherein the second portion ofthe base layer is a portion of the base layer where the gate electrodeis not overlapping the base layer, and wherein the second portion of thebase layer is in contact with the first portion of the base layer.
 2. Amethod for manufacturing a display device according to claim 1, whereinthe microcrystalline semiconductor has a Raman spectrum having a Si-Sipeak at a lower wavenumber than 520 cm⁻¹.
 3. A method for manufacturinga display device according to claim 1, further comprising to formscanning lines and signal lines over the substrate, wherein the scanninglines and the signal lines are controlled by external driver circuits.4. A method for manufacturing a display device according to claim 1,wherein the gate insulating film comprises a first silicon nitridelayer, a silicon oxide layer, and a second silicon nitride layer.
 5. Amethod for manufacturing a display device according to claim 1, furthercomprising to form a protective diode over the substrate.
 6. A methodfor manufacturing a display device according to claim 1, wherein aprotective layer over the second semiconductor layer comprises one ofsilicon nitride and silicon nitride oxide.
 7. A method for manufacturinga display device according to claim 1, wherein the metal material is ametal selected from the group consisting of Ti (titanium), W (tungsten),Cr (chromium), Ta (tantalum), Ni (nickel), or Mo (molybdenum); or anoxide thereof.
 8. A method for manufacturing a display devicecomprising: forming a base layer comprising a metal material over asubstrate; forming a gate electrode over a first portion of the baselayer; insulating a second portion of the base layer; forming a gateinsulating film over the gate electrode and the second portion of thebase layer, the gate insulating film comprising a plurality ofinsulating layers; forming a first semiconductor layer over the gateinsulating film, the first semiconductor layer comprising amicrocrystalline semiconductor; forming an insulating layer on the firstsemiconductor layer; forming a second semiconductor layer over the firstsemiconductor layer and the insulating layer; etching the firstsemiconductor layer and the second semiconductor layer, thereby forminga semiconductor island and an impurity region over the semiconductorisland, and the insulating layer interposed therebetween; forming sourceand drain wiring layers over the impurity region; and etching theimpurity region using the source and drain wiring layers as masks,thereby forming source and drain regions, wherein the second portion ofthe base layer is a portion of the base layer where the gate electrodeis not overlapping the base layer, and wherein the second portion of thebase layer is in contact with the first portion of the base layer.
 9. Amethod for manufacturing a display device according to claim 8, whereinthe microcrystalline semiconductor has a Raman spectrum having a Si-Sipeak at a lower wavenumber than 520 cm⁻¹.
 10. A method for manufacturinga display device according to claim 8, further comprising to formscanning lines and signal lines over the substrate, wherein the scanninglines and the signal lines are controlled by external driver circuits.11. A method for manufacturing a display device according to claim 8,wherein the gate insulating film comprises a first silicon nitridelayer, a silicon oxide layer, and a second silicon nitride layer.
 12. Amethod for manufacturing a display device according to claim 8, furthercomprising to form a protective diode over the substrate.
 13. A methodfor manufacturing a display device according to claim 8, wherein aprotective layer over the second semiconductor layer comprises one ofsilicon nitride and silicon nitride oxide.
 14. A method formanufacturing a display device according to claim 8, wherein the metalmaterial is a metal selected from the group consisting of Ti (titanium),W (tungsten), Cr (chromium), Ta (tantalum), Ni (nickel), or Mo(molybdenum); or an oxide thereof.
 15. A method for manufacturing adisplay device comprising: forming a base layer comprising a metalmaterial over a substrate; forming a gate electrode over a first portionof the base layer; insulating a second portion of the base layer;forming a gate insulating film over the gate electrode and the secondportion of the base layer, the gate insulating film comprising aplurality of insulating layers; forming a first semiconductor layer overthe gate insulating film, the first semiconductor layer comprising amicrocrystalline semiconductor; forming a second semiconductor layerover the first semiconductor layer; etching the first semiconductorlayer and the second semiconductor layer, thereby forming asemiconductor island and an impurity region over the semiconductorisland; forming source and drain wiring layers over the impurity region;and etching the impurity region and a portion of the semiconductorisland using the source and drain wiring layers as masks, therebyforming source and drain regions, wherein the second portion of the baselayer is a portion of the base layer where the gate electrode is notoverlapping the base layer, and wherein the second portion of the baselayer is in contact with the first portion of the base layer.
 16. Amethod for manufacturing a display device according to claim 15, whereinthe microcrystalline semiconductor has a Raman spectrum having a Si-Sipeak at a lower wavenumber than 520 cm⁻¹.
 17. A method for manufacturinga display device according to claim 15, further comprising to formscanning lines and signal lines over the substrate, wherein the scanninglines and the signal lines are controlled by external driver circuits.18. A method for manufacturing a display device according to claim 15,wherein the gate insulating film comprises a first silicon nitridelayer, a silicon oxide layer, and a second silicon nitride layer.
 19. Amethod for manufacturing a display device according to claim 15, furthercomprising to form a protective diode over the substrate.
 20. A methodfor manufacturing a display device according to claim 15, wherein aprotective layer over the second semiconductor layer comprises one ofsilicon nitride and silicon nitride oxide.
 21. A method formanufacturing a display device according to claim 15, wherein the metalmaterial is a metal selected from the group consisting of Ti (titanium),W (tungsten), Cr (chromium), Ta (tantalum), Ni (nickel), or Mo(molybdenum); or an oxide thereof.